Micro gear is the key element of micro-electro-mechanical system(MEMS). The tooth surface wear is one of the main factors affecting its service performance and failure mode. In order to study the wear mechanisms of micro gear, the UMESHMOTION subroutine in ABAQUS is developed based on the Archard wear theory, and a finite element analysis model of the wear in micro gear is established combining with ALE adaptive mesh technology. Then, the tooth surface wear distribution under different meshing periods is obtained and verified. Based on the constructed finite element model, considering the interaction of the master and slave tooth surface wear, the influence of different material properties (modulus of elasticity) and material pairing on the tooth surface wear distribution are analyzed. The results show that the most serious wear of the micro gear tooth surface occurs at the base circle near the tooth root, and the wear near the tooth tip is lighter; compared with the material properties, different material pairing has a more significant effect on the wear of the micro gear.