To set up the accurate mathematical model of airplane synchronous generator is the key technology for AVR dynamic performance test. Dealing with the application background of AVR dynamic performance test, a novel idea of setting up the non-linear model of synchronous generator using the modularization method is proposed. A wavelet neutron network model of the impact load and impact unload characteristics of synchronous generator is set up based on WNN. The accuracy of this model is verified using the pre-distributed verification data, and the model for AVR dynamic performance test is feasible.