The invention discloses a historical data service system used for a smart power grid dispatching control system, and inquires historical data on the basis of a cache management mechanism and a historical library access monitoring mechanism. The historical data service system comprises a management control module, a data cache region module and a relational database interaction module, wherein the management control module consists of a curve template and a task distributor module; the data cache region module consists of a data cache region, a data index table, a cache data synchronization module and a data point replacement algorithm module; and the relational database interaction module consists of a data interaction module and a dialogue monitoring module. The historical data service system adopts a historical data cache management mechanism to improve service query efficiency and lighten relational database load. A database dialogue monitoring mechanism is adopted to improve service stability.