diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/PartitioningUtils.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/PartitioningUtils.scala
index a2e08180cc50e..0625cfb772da2 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/PartitioningUtils.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/PartitioningUtils.scala
@@ -122,6 +122,13 @@ object PartitioningUtils {
       Map.empty[String, DataType]
     }
 
+    // SPARK-26990: use user specified field names if case insensitive.
+    val userSpecifiedNames = if (userSpecifiedSchema.isDefined && !caseSensitive) {
+      CaseInsensitiveMap(userSpecifiedSchema.get.fields.map(f => f.name -> f.name).toMap)
+    } else {
+      Map.empty[String, String]
+    }
+
     val dateFormatter = DateFormatter()
     val timestampFormatter = TimestampFormatter(timestampPartitionPattern, timeZone)
     // First, we need to parse every partition's path and see if we can find partition values.
@@ -170,7 +177,9 @@ object PartitioningUtils {
         columnNames.zip(literals).map { case (name, Literal(_, dataType)) =>
           // We always assume partition columns are nullable since we've no idea whether null values
           // will be appended in the future.
-          StructField(name, userSpecifiedDataTypes.getOrElse(name, dataType), nullable = true)
+          val resultName = userSpecifiedNames.getOrElse(name, name)
+          val resultDataType = userSpecifiedDataTypes.getOrElse(name, dataType)
+          StructField(resultName, resultDataType, nullable = true)
         }
       }
 
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/FileIndexSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/FileIndexSuite.scala
index 6bd0a2591fc1f..e0a3641218343 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/FileIndexSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/FileIndexSuite.scala
@@ -65,6 +65,21 @@ class FileIndexSuite extends SharedSQLContext {
     }
   }
 
+  test("SPARK-26990: use user specified field names if possible") {
+    withTempDir { dir =>
+      val partitionDirectory = new File(dir, "a=foo")
+      partitionDirectory.mkdir()
+      val file = new File(partitionDirectory, "text.txt")
+      stringToFile(file, "text")
+      val path = new Path(dir.getCanonicalPath)
+      val schema = StructType(Seq(StructField("A", StringType, false)))
+      withSQLConf(SQLConf.CASE_SENSITIVE.key -> "false") {
+        val fileIndex = new InMemoryFileIndex(spark, Seq(path), Map.empty, Some(schema))
+        assert(fileIndex.partitionSchema.length == 1 && fileIndex.partitionSchema.head.name == "A")
+      }
+    }
+  }
+
   test("SPARK-26230: if case sensitive, validate partitions with original column names") {
     withTempDir { dir =>
       val partitionDirectory = new File(dir, "a=1")