diff --git a/paddle/parameter/FirstOrderOptimizer.cpp b/paddle/parameter/FirstOrderOptimizer.cpp
index 02e600adb9e88803fbb54792c307ba4abaf8e570..207fb33f4e88cc8a4467ed7dc35003f348fbf3cf 100644
--- a/paddle/parameter/FirstOrderOptimizer.cpp
+++ b/paddle/parameter/FirstOrderOptimizer.cpp
@@ -305,12 +305,13 @@ void AdamaxParameterOptimizer::update(const VectorPtr vecs[],
 void OptimizerWithGradientClipping::update(const VectorPtr vecs[],
                                            const ParameterConfig& config,
                                            size_t sparseId) const {
-  // globalGradientClipping(vecs, config, FLAGS_log_clipping);
   real global_thres_ = optConfig_.gradient_clipping_threshold();
   real local_thres_ = config.gradient_clipping_threshold();
 
   real threshold;
   std::string field;
+  // Get the minimum of local and global threshold
+  // as the real threshold for clipping
   if (global_thres_ > 0.0f && local_thres_ > 0.0f) {
     threshold = global_thres_ < local_thres_ ? global_thres_ : local_thres_;
     field = global_thres_ < local_thres_ ? "global" : "local";
diff --git a/paddle/parameter/ParameterOptimizer.h b/paddle/parameter/ParameterOptimizer.h
index 38d432ba9bc4d84edcdcfd93faf00b7181b385a5..f98ba569b569379b30d034739a7f84aaf97108db 100644
--- a/paddle/parameter/ParameterOptimizer.h
+++ b/paddle/parameter/ParameterOptimizer.h
@@ -170,9 +170,6 @@ public:
 
   real getLearningRate() const { return learningRate_; }
 
-  // real getGradientClippingThreshold() const {return
-  // gradientClippingThreshold_;}
-
   virtual void setNoDecay() { applyDecay_ = false; }
 
   static ParameterOptimizer* create(const OptimizationConfig& optConfig,
@@ -206,11 +203,6 @@ protected:
    */
   real learningRate_;
 
-  /**
-   * global threshold for gradient clipping,
-   * init value is opt_config.gradient_clipping_thresholod
-   */
-
   std::unique_ptr<LearningRateScheduler> learningRateScheduler_;
   int64_t pass_;  // current training pass (starting from 0)
   bool firstTime_;