Abstract: Objective: Adverse conditions such as hard points on the overhead line of operating routes, abnormal PC (pantographcatenary) contact force and PC arcing can affect metro normal operation. Therefore, it is necessary to study methods that can accurately identify sections with abnormal PC contact force and locate overhead line hard points along the operating route.Method: Existing sensing technology and MOMS (microoptomechanical systems) sensing technology are introduced. A realtime monitoring system for metro PC relation based on MOMS sensing technology is proposed. Monitored results of overhead line hard points, PC contact force and PC arcing are analyzed.Result & Conclusion: When the train operating speed is 80 km/h, the dynamic PC contact force monitored by the MOMS contact force sensors is approximately 120 N ± 10 N. The MOMS accelerometers capture the instantaneous vibration impact on the pantograph head caused by overhead line hard points, with the vertical acceleration changing from -200g to 120g. The fluctuation level of the PC interaction can indirectly evaluate the occurrence of PC arcing.