Aiming at the output characteristics of diesel generator set with pulse load, an index is proposed to evaluate the consistency of output voltage (current) waveform to judge the simulation degree of the model. Also, a dynamic limiting method for synchronous generator excitation voltage output based on BP neural network algorithm is proposed, and it is applied to the model optimization of diesel generator set. Experimental results show that among the 27 sets of examples, 18 groups’ real-time waveform proximity (RWP) values are less than 90% in the original simulation but in the optimized simulation, the RWP values of all the test groups are higher than 90%, indicating that the optimized simulation model is more effective, and can be applied to further research on diesel generator set with pulse load.