Motion features of the modern aircraft are becoming much more complex.The change of antenna coverage properties caused by the change of aircraft attitude may result the change of signal gain in the antenna frontend.The traditional method of GPS signal simulation did not take the above effects into consideration.In order to reflect the influence of carrier attitude on GPS signal,the antenna lobe pattern, coordinate system transformation and aircraft attitude were integrated together to deduce the model of GPS signal gain.This study can provide a reference for the engineering application of satellite signal simulation.