Surface plasmon resonance (SPR) has tremendous application value in biosensing. The phase sensing of the resonant angle based on a prism structure exhibits higher sensitivity compared with the reflectivity sensing. Multi-channel real-time phase shift detection is a research highlight in SPR biosensing. An SPR phase detection system based on Kretschmann prism structure attenuated total reflection (ATR) single- path is proposed. The phase difference between P-polarized signal light and S-polarized reference light is controlled by a liquid crystal variable retarder (LCVR) to realize single-path interference. Fixed-point phase detection of two-dimensional surfaces is realized by an addressable micro-mirror array (MMA). The system can detect the phase shift information with a spatial resolution close to a single MMA pixel (7.64 μm horizontally/vertically or 10.8 μm diagonally). It is capable of realizing single-path, high-precision, multi-channel two-dimensional plasmon resonance phase shift detection, providing new experimental ideas for in-situ biosensors and phase imaging beyond diffraction limits.