To solve the problem that manual intervention is required in the design of the classifier of the decision tree in radar jamming signal recognition, a method for automatic design of the decision tree based on fuzzy clustering, Xie-Beni index and information gain is proposed.Firstly, the feature set of the parameters of the jamming signal in such dimensions as the time domain, the frequency domain and the time domain after pulse compression is established.Then, Fuzzy C-Means (FCM) clustering is introduced in the process of decision tree establishment, so as to solve the problem that the traditional decision tree needs prior knowledge to set the decision threshold.Then, Xie-Beni index is used to dynamically determine the number of branches of decision tree nodes and lower the complexity of the decision tree.Finally, the ID3 algorithm based on information gain is used to establish the fuzzy-clustering decision tree.This method realizes the automatic design of the decision tree in jamming signal recognition and optimizes the performance of the decision tree.Computer simulation and the experimental data of radar countermeasure have verified the effectiveness of this method.