Aim To study the method for reducing mounting system vibration of high power engine. Methods The six degrees of freedom dynamic model of engine is constructed by analytical theory of vibration. The system equations are solved by optimal method. An all purpose program is developed to simulate the process. Results Mounting system of a military diesel engine is opimized by the program. The calculated result is consistent with the experimental result. Conclusion The optimal method and the program can be generally used to design mounting system of other high power engines and to predict their vibration intention.