Surface plasmon resonance can be excited on 52.3 nm gold film through a large numerical aperture microscope objective lens (oil immersion) based on Kretschmann configuration. According to Maxwell’s equations and Fresnel’s formula, a mathematics model of the structure is established, and the intensity distribution at the back focal plane of the objective lens is simulated using Matlab and collected by imaging sensor and processed in computer. Experiment results agree well with theoretical result. The analysis of the numerical simulation and measuring result provide certain theoretical and experimental basis for the application of surface plasmon resonance imaging and refractive index detection of analyte attached to gold film.