diff --git a/config/set/symfony/symfony30.yaml b/config/set/symfony/symfony30.yaml
index 631cc1a11a3..6cfb78b9702 100644
--- a/config/set/symfony/symfony30.yaml
+++ b/config/set/symfony/symfony30.yaml
@@ -12,6 +12,7 @@ services:
     Rector\Symfony\Rector\MethodCall\FormTypeInstanceToClassConstRector: null
     Rector\Symfony\Rector\Form\StringFormTypeToClassRector: null
     Rector\Symfony\Rector\MethodCall\CascadeValidationFormBuilderRector: null
+    Rector\Symfony\Rector\ClassMethod\RemoveDefaultGetBlockPrefixRector: null
 
     # forms - collection
     Rector\Symfony\Rector\MethodCall\ChangeCollectionTypeOptionTypeFromStringToClassReferenceRector: null
diff --git a/docs/rector_rules_overview.md b/docs/rector_rules_overview.md
index f384dc54ddf..e72d243a7e4 100644
--- a/docs/rector_rules_overview.md
+++ b/docs/rector_rules_overview.md
@@ -1,4 +1,4 @@
-# All 523 Rectors Overview
+# All 524 Rectors Overview
 
 - [Projects](#projects)
 - [General](#general)
@@ -65,7 +65,7 @@
 - [SOLID](#solid) (12)
 - [Sensio](#sensio) (3)
 - [StrictCodeQuality](#strictcodequality) (1)
-- [Symfony](#symfony) (32)
+- [Symfony](#symfony) (33)
 - [SymfonyCodeQuality](#symfonycodequality) (1)
 - [SymfonyPHPUnit](#symfonyphpunit) (1)
 - [Twig](#twig) (1)
@@ -11148,6 +11148,27 @@ Turns redirect to route to short helper method in Controller in Symfony
 
 <br><br>
 
+### `RemoveDefaultGetBlockPrefixRector`
+
+- class: [`Rector\Symfony\Rector\ClassMethod\RemoveDefaultGetBlockPrefixRector`](/../master/rules/symfony/src/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector.php)
+- [test fixtures](/../master/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/Fixture)
+
+Rename `getBlockPrefix()` if it returns the default value - class to underscore, e.g. UserFormType = user_form
+
+```diff
+ use Symfony\Component\Form\AbstractType;
+
+ class TaskType extends AbstractType
+ {
+-    public function getBlockPrefix()
+-    {
+-        return 'task';
+-    }
+ }
+```
+
+<br><br>
+
 ### `ResponseStatusCodeRector`
 
 - class: [`Rector\Symfony\Rector\BinaryOp\ResponseStatusCodeRector`](/../master/rules/symfony/src/Rector/BinaryOp/ResponseStatusCodeRector.php)
diff --git a/rules/symfony/src/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector.php b/rules/symfony/src/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector.php
new file mode 100644
index 00000000000..de99a9210ee
--- /dev/null
+++ b/rules/symfony/src/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector.php
@@ -0,0 +1,120 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Symfony\Rector\ClassMethod;
+
+use Nette\Utils\Strings;
+use PhpParser\Node;
+use PhpParser\Node\Expr;
+use PhpParser\Node\Stmt\ClassMethod;
+use PhpParser\Node\Stmt\Return_;
+use Rector\Core\Rector\AbstractRector;
+use Rector\Core\RectorDefinition\CodeSample;
+use Rector\Core\RectorDefinition\RectorDefinition;
+use Rector\Core\Util\StaticRectorStrings;
+use Rector\NodeTypeResolver\Node\AttributeKey;
+
+/**
+ * @see https://github.com/symfony/symfony/blob/3.4/UPGRADE-3.0.md#form
+ *
+ * @see \Rector\Symfony\Tests\Rector\ClassMethod\RemoveDefaultGetBlockPrefixRector\RemoveDefaultGetBlockPrefixRectorTest
+ */
+final class RemoveDefaultGetBlockPrefixRector extends AbstractRector
+{
+    public function getDefinition(): RectorDefinition
+    {
+        return new RectorDefinition(
+            'Rename `getBlockPrefix()` if it returns the default value - class to underscore, e.g. UserFormType = user_form',
+            [
+                new CodeSample(
+                    <<<'PHP'
+use Symfony\Component\Form\AbstractType;
+
+class TaskType extends AbstractType
+{
+    public function getBlockPrefix()
+    {
+        return 'task';
+    }
+}
+PHP
+,
+                    <<<'PHP'
+use Symfony\Component\Form\AbstractType;
+
+class TaskType extends AbstractType
+{
+}
+PHP
+
+                ),
+            ]
+        );
+    }
+
+    /**
+     * @return string[]
+     */
+    public function getNodeTypes(): array
+    {
+        return [ClassMethod::class];
+    }
+
+    /**
+     * @param ClassMethod $node
+     */
+    public function refactor(Node $node): ?Node
+    {
+        if (! $this->isObjectMethodNameMatch($node)) {
+            return null;
+        }
+
+        $returnedExpr = $this->resolveOnlyStmtReturnExpr($node);
+        if ($returnedExpr === null) {
+            return null;
+        }
+
+        $returnedValue = $this->getValue($returnedExpr);
+
+        $classShortName = $node->getAttribute(AttributeKey::CLASS_SHORT_NAME);
+        if (Strings::endsWith($classShortName, 'Type')) {
+            $classShortName = Strings::before($classShortName, 'Type');
+        }
+
+        $underscoredClassShortName = StaticRectorStrings::camelCaseToUnderscore($classShortName);
+        if ($underscoredClassShortName !== $returnedValue) {
+            return null;
+        }
+
+        $this->removeNode($node);
+
+        return null;
+    }
+
+    /**
+     * return <$thisValue>;
+     */
+    private function resolveOnlyStmtReturnExpr(ClassMethod $classMethod): ?Expr
+    {
+        if (count((array) $classMethod->stmts) !== 1) {
+            return null;
+        }
+
+        $onlyStmt = $classMethod->stmts[0];
+        if (! $onlyStmt instanceof Return_) {
+            return null;
+        }
+
+        return $onlyStmt->expr;
+    }
+
+    private function isObjectMethodNameMatch(ClassMethod $classMethod): bool
+    {
+        if (! $this->isInObjectType($classMethod, 'Symfony\Component\Form\AbstractType')) {
+            return false;
+        }
+
+        return $this->isName($classMethod->name, 'getBlockPrefix');
+    }
+}
diff --git a/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/Fixture/double_name.php.inc b/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/Fixture/double_name.php.inc
new file mode 100644
index 00000000000..f830580efc8
--- /dev/null
+++ b/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/Fixture/double_name.php.inc
@@ -0,0 +1,27 @@
+<?php
+
+namespace Rector\Symfony\Tests\Rector\ClassMethod\RemoveDefaultGetBlockPrefixRector\Fixture;
+
+use Symfony\Component\Form\AbstractType;
+
+class DoubleNameType extends AbstractType
+{
+    public function getBlockPrefix()
+    {
+        return 'double_name';
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Symfony\Tests\Rector\ClassMethod\RemoveDefaultGetBlockPrefixRector\Fixture;
+
+use Symfony\Component\Form\AbstractType;
+
+class DoubleNameType extends AbstractType
+{
+}
+
+?>
diff --git a/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/Fixture/fixture.php.inc b/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/Fixture/fixture.php.inc
new file mode 100644
index 00000000000..77a52555f9a
--- /dev/null
+++ b/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/Fixture/fixture.php.inc
@@ -0,0 +1,27 @@
+<?php
+
+namespace Rector\Symfony\Tests\Rector\ClassMethod\RemoveDefaultGetBlockPrefixRector\Fixture;
+
+use Symfony\Component\Form\AbstractType;
+
+class TaskType extends AbstractType
+{
+    public function getBlockPrefix()
+    {
+        return 'task';
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Symfony\Tests\Rector\ClassMethod\RemoveDefaultGetBlockPrefixRector\Fixture;
+
+use Symfony\Component\Form\AbstractType;
+
+class TaskType extends AbstractType
+{
+}
+
+?>
diff --git a/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/Fixture/skip_different_name.php.inc b/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/Fixture/skip_different_name.php.inc
new file mode 100644
index 00000000000..7396d1d5841
--- /dev/null
+++ b/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/Fixture/skip_different_name.php.inc
@@ -0,0 +1,13 @@
+<?php
+
+namespace Rector\Symfony\Tests\Rector\ClassMethod\RemoveDefaultGetBlockPrefixRector\Fixture;
+
+use Symfony\Component\Form\AbstractType;
+
+class SkipDifferentNameType extends AbstractType
+{
+    public function getBlockPrefix()
+    {
+        return 'unique';
+    }
+}
diff --git a/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/RemoveDefaultGetBlockPrefixRectorTest.php b/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/RemoveDefaultGetBlockPrefixRectorTest.php
new file mode 100644
index 00000000000..fe6dee32e4a
--- /dev/null
+++ b/rules/symfony/tests/Rector/ClassMethod/RemoveDefaultGetBlockPrefixRector/RemoveDefaultGetBlockPrefixRectorTest.php
@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Symfony\Tests\Rector\ClassMethod\RemoveDefaultGetBlockPrefixRector;
+
+use Iterator;
+use Rector\Core\Testing\PHPUnit\AbstractRectorTestCase;
+use Rector\Symfony\Rector\ClassMethod\RemoveDefaultGetBlockPrefixRector;
+use Symplify\SmartFileSystem\SmartFileInfo;
+
+final class RemoveDefaultGetBlockPrefixRectorTest extends AbstractRectorTestCase
+{
+    /**
+     * @dataProvider provideData()
+     */
+    public function test(SmartFileInfo $fileInfo): void
+    {
+        $this->doTestFileInfo($fileInfo);
+    }
+
+    public function provideData(): Iterator
+    {
+        return $this->yieldFilesFromDirectory(__DIR__ . '/Fixture');
+    }
+
+    protected function getRectorClass(): string
+    {
+        return RemoveDefaultGetBlockPrefixRector::class;
+    }
+}