In high-speed integrated power units, vibration signal coupling is very serious, which makes it difficult to determine the number of vibration sources by using traditional methods. In order to cope with this problem, this paper proposed an improved blind source signal processing method. Based on the traditional blind source separation method, this method used prior knowledge of failure mechanism to enhance the effect of blind source separation. Experiment results show that signal after separation fits well with fault characteristics. This method is very effective in the fault diagnosis of integrated power unit and it can improve the accuracy of fault diagnosis.