The invention discloses a substation protection press plate position on-line monitoring system which comprises an upper computer, intelligent press plate managers and intelligent press plates. The intelligent press plate managers collect information of the intelligent press plates, forward commands sent by the upper computer, carry out relay and data conversion on various parameters of the intelligent press plates, and send the processed data to the upper computer through an RS485 communication line. Position in-service/out-of-service states of the press plates are subjected to on-line monitoring by utilizing the non-electrical principle, and thus the problems of in-service/out-of-service leak and in-service/out-of-service misoperaiton of the press plates are solved, and a complete mis-locking-prevention scheme from primary equipment to secondary equipment is formed.