The gear system in an aircraft engine operates under harsh conditions, subjected to high-speed and heavy-load situations. High sliding velocity and load lead to non-uniform wear on the gear surfaces. The tooth surface wear alter the tooth profile, affect the normal meshing of gear consequently. In order to reveal the non-uniform wear characteristics for the gear pairs, based on the timing-varying stiffness of meshing gear pair, a lumped parameter model of gear pair with nonlinear internal excitation is established. Based on the gear meshing contact and motion analysis, a parameterized model of the gear pair, incorporating nonlinear internal excitation, is constructed. Combined with the line contact mixed EHL model, the tooth surface contact temperature is calculated by considering the comprehensive friction coefficient and heat flux density. According to the classical Archard wear calculation theory, a simulation model of spur gear tooth surface wear considering mixed EHL is constructed to calculate the distribution of wear on the tooth profile.