Abstract: The state-of-the-art study shows that extracting the code features from a large amount of source codes and building the statistical language model have good predictive ability for the codes.However,the present methods still can be polished in the predicting accuracy,because when they build the existing statistical language model,the text information in the codes is often used as feature words,which means that the syntax structure information of the codes can not be fully utilized.In order to improve the predicting performance of the code,this paper proposed the concept of the constraint relation of methods.Based on this,this paper studied the method invocation sequence of Java objects,abstracted code features,and built the statistical language model to complete the code prediction.Moreover,this paper studied the application scope of the prediction model based on the method constraint relationship in Java language.Experiments show that this method improves the accuracy by 8% compared with the existing model.