The invention discloses a master station system suitable for operation and maintenance management of secondary equipment of a power grid. The master station system comprises six modules for data acquisition, warning monitoring and management, secondary equipment inspection, running state estimation of the secondary equipment, defect diagnosis and management, monitoring and early-warning analysis and human-computer operation main interface. Panorama information of microcomputer protection is collected to an on-line management centralized control unit in a substation through a communication network by the master station system according to a unified data transmission standard, data is analyzed and processed, the information is remotely transmitted to a scheduling master station end, intelligent query or an intelligent diagnosis relevant function is provided, so that the operation maintenance and inspection frequency of the substation operation maintenance worker on a site relay protection device is reduced, and the delicacy management level of the equipment is improved.