The invention discloses an array type online monitoring system for protective pressure plates of a substation. The system comprises a state monitoring mechanism, an error compensating mechanism, a data collection mechanism and an information processing mechanism which are successively connected; the state monitoring mechanism comprises a broadband light source and a plurality of optical fiber grating sensors; the optical fiber grating sensors are successively connected from end to end through an optical fiber line; the optical fiber grating sensors are arrayed on a protection screen corresponding to the protection pressure plates; the optical fiber grating sensors are arranged at one sides of the protection pressure plates; and when the connecting plates of the protection pressure plates are withdrawn, the connecting plates can be rotated to contact with the optical fiber grating sensors. According to the system provided by the invention, the throwing and withdrawing of the pressure protection plates are monitored on line in real time; and through adoption of the new type monitoring technique, the influence of an electromagnetic environment on monitoring accuracy is avoided.