diff --git a/python/pyspark/ml/param/_shared_params_code_gen.py b/python/pyspark/ml/param/_shared_params_code_gen.py
index 5d0183f183ef0..5e297b8214823 100644
--- a/python/pyspark/ml/param/_shared_params_code_gen.py
+++ b/python/pyspark/ml/param/_shared_params_code_gen.py
@@ -175,12 +175,11 @@ def __init__(self):
         super(DecisionTreeParams, self).__init__()'''
     dtParamMethods = ""
     dummyPlaceholders = ""
-    realParams = ""
     paramTemplate = """$name = Param($owner, "$name", "$doc")"""
     for name, doc in decisionTreeParams:
         variable = paramTemplate.replace("$name", name).replace("$doc", doc)
         dummyPlaceholders += variable.replace("$owner", "Params._dummy()") + "\n    "
         dtParamMethods += _gen_param_code(name, doc, None) + "\n"
-    code.append(decisionTreeCode.replace("$dummyPlaceHolders", dummyPlaceholders) +
+    code.append(decisionTreeCode.replace("$dummyPlaceHolders", dummyPlaceholders) + "\n" +
                 dtParamMethods)
     print("\n\n\n".join(code))
diff --git a/python/pyspark/ml/param/shared.py b/python/pyspark/ml/param/shared.py
index b74214255156b..db4a8a54d4956 100644
--- a/python/pyspark/ml/param/shared.py
+++ b/python/pyspark/ml/param/shared.py
@@ -574,6 +574,7 @@ class DecisionTreeParams(Params):
 
     def __init__(self):
         super(DecisionTreeParams, self).__init__()
+
     def setMaxDepth(self, value):
         """
         Sets the value of :py:attr:`maxDepth`.
diff --git a/python/pyspark/ml/regression.py b/python/pyspark/ml/regression.py
index ba0d182e2ac5a..74a2248ed07c8 100644
--- a/python/pyspark/ml/regression.py
+++ b/python/pyspark/ml/regression.py
@@ -600,6 +600,9 @@ def __init__(self, featuresCol="features", labelCol="label", predictionCol="pred
         """
         super(GBTRegressor, self).__init__()
         self._java_obj = self._new_java_obj("org.apache.spark.ml.regression.GBTRegressor", self.uid)
+        self._setDefault(maxDepth=5, maxBins=32, minInstancesPerNode=1, minInfoGain=0.0,
+                         maxMemoryInMB=256, cacheNodeIds=False, subsamplingRate=1.0,
+                         checkpointInterval=10, lossType="squared", maxIter=20, stepSize=0.1)
         kwargs = self.__init__._input_kwargs
         self.setParams(**kwargs)