Surface plasmon resonance (SPR) is a phenomenon induced by the polarizing energy coupling and resonant exciting of surface plasmon wave and incident TM light wave. The SPR on gold film is studied with combination of scanning near-field optical microscope (SNOM) and SPR technique. A novel Kretschmann type of SPR coupling device with special structure is designed and set up, and the fabrication method of surface plasmon with thickness gradient is presented. Based on the above preparation, the curve of SPR is measured with varied incident angle conditions, and the angle sensitivity for SPR is 1°. The image of gold film surface is obtained with SNOM under PSR conditions, and it is found that the image is clearer under SPR condition than that without SPR and more details are distinguished. The performances, such as signal-noise ratio and resolution, for SNOM are greatly improved with the SPR technique.