Abstract: The mean value model for small two stroke gasoline aero-engine based on the mechanism modeling and experiment modeling combined method was presented.The two stroke gasoline engine mean value model mainly consists of three dynamic modules: the fuel evaporation and oil film dynamic module,the intake port and crankcase scavenging module,power output module.The reed valve modeling and the short circuit loss during scavenging process were also considered at the modeling process.Then established the power output,rotational speed and Air/Fuel ratio models,and carried out simulation on Matlab/Simulink platform.The simulation result fully meets the experiment data,which proves the correctness of the mean value model.