diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala
index 3de9f5a951fe..4c5419961ee9 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala
@@ -620,6 +620,12 @@ case class Cast(child: Expression, dataType: DataType, timeZoneId: Option[String
     // We can return what the children return. Same thing should happen in the codegen path.
     if (DataType.equalsStructurally(from, to)) {
       identity
+    } else if (from == NullType) {
+      // According to `canCast`, NullType can be casted to any type.
+      // For primitive types, we don't reach here because the guard of `nullSafeEval`.
+      // But for nested types like struct, we might reach here for nested null type field.
+      // We won't call the returned function actually, but returns a placeholder.
+      _ => throw new SparkException(s"should not directly cast from NullType to $to.")
     } else {
       to match {
         case dt if dt == from => identity[Any]
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala
index 1b7f2581f895..f6a1d00c519c 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala
@@ -990,4 +990,19 @@ class CastSuite extends SparkFunSuite with ExpressionEvalHelper {
       }
     }
   }
+
+  test("SPARK-27671: cast from nested null type in struct") {
+    import DataTypeTestUtils._
+
+    atomicTypes.foreach { atomicType =>
+      val struct = Literal.create(
+        InternalRow(null),
+        StructType(Seq(StructField("a", NullType, nullable = true))))
+
+      val ret = cast(struct, StructType(Seq(
+        StructField("a", atomicType, nullable = true))))
+      assert(ret.resolved)
+      checkEvaluation(ret, InternalRow(null))
+    }
+  }
 }
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala
index 8c859f7dba5e..dd3740d24f72 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala
@@ -2157,4 +2157,13 @@ class DataFrameSuite extends QueryTest with SharedSQLContext {
           |*(1) Range (0, 10, step=1, splits=2)""".stripMargin))
     }
   }
+
+  test("SPARK-27671: Fix analysis exception when casting null in nested field in struct") {
+    val df = sql("SELECT * FROM VALUES (('a', (10, null))), (('b', (10, 50))), " +
+      "(('c', null)) AS tab(x, y)")
+    checkAnswer(df, Row("a", Row(10, null)) :: Row("b", Row(10, 50)) :: Row("c", null) :: Nil)
+
+    val cast = sql("SELECT cast(struct(1, null) AS struct<a:int,b:int>)")
+    checkAnswer(cast, Row(Row(1, null)) :: Nil)
+  }
 }