This paper presents a surface plasmon resonance (SPR) imaging system based on angular modulation (AM) and intensity measurement (IM) together to avoid the mechanical errors of the angle scanning device. The SPR resonant angle was found by angular scanning method and then the light intensity changes were collected at a fixed incident angle. Glycerol gradient solution (0%, 1%, 2%, 3% (weight percentage) glycerol dissolved in water) experiments were conducted, which indicate that the best fixed angle location is the middle of the linear range of SPR absorption peak and the central area signals are more uniform than those of the border areas. The sensitivity differences of different areas of SPR images are studied, and an optimized algorithm is developed.