Relay protection devices which play an important role in the secondary protection system should be checked periodically. Massive core information that created by the in-station systems could be used for status evaluation, to reduce the frequency of regular on-site inspection. All data uploaded to master stations in grid control center could be classified based on their characteristics into four classes as raw electric data, hard data, soft data and recording data. Application systems communicating with stations in grid control center are regarded as data sources, and their upload contents and features are analyzed. Proper extraction procedures could be executed to ensure accuracy and reliability. Time alignment, error elimination and sorting are introduced as key steps in sequence to generate processed data. Status verification sub-system are in development as one part of monitoring system and several functions are provided by digging and utilizing these data, giving the maintenance personal capabilities to verify status of devices of unattended and remote region substations.