The invention provides a mass data management method of a power grid. The method comprises the following steps: constructing a power grid user data management system, integrating data collected by each power grid subsystem, and utilizing a parallel computing frame to mine and analyze power grid user data; and on the basis of the data management system, utilizing a distributed load prediction algorithm to realize parallel load prediction. The invention provides the mass data management method of the power grid, the data of each system of the power grid user is fused and integrated, and a traditional data computation method is migrated to a distributed platform to meet the operation requirements of the mass data.