Through the analysis of PAC module faults in two GE Signa HDxt 1.5 T MRI cases, the fault performance was analyzed. According to the working principle of PAC module, the fault was analyzed and processed, and then the suspicious fault parts were located and repaired to make the equipment run normally. Finally, the operating principles of PAC module in terms of power supply, signal transmission and data transmission were summarized to facilitate the subsequent quickly and find out fault points for maintenance accurately.