Based on the principle of surface plasmon resonance (SPR) sensor, the influence of mental film was illuminated. According to the MATLAB simulation, the performance of SPR sensor using Au and Ag film was compared. The optimal thickness was 52nm and 38nm, respectively. In view of the features of Au and Ag film, Ag+Au hybrid metal film was proposed. On the basis of simulated result, it could be concluded that the performance of SPR sensor with 50nm composite film (Ag film 20nm ) was excellent.