Abstract: The influence of chemical surface treatment on charge stability for miniature Si₃N₄/SiO₂ films was discussed,the inhibit effect of the surface treatment to the lateral diffusion of detrapping charge was investigated.For different chemical reagents,the charge stability and their dynamic of miniature samples after the treatment were studied by comparing the results of surface potential decay under high-temperature and high-humidity conditions between the miniature Si₃N₄/SiO₂ electret film and the bulk film based on silicon.