Abstract: Aiming at improving the power factor of coal mine power grid, this paper proposes a real-time online method to improve the power factor of coal mine power grids. Firstly, utilizing the power grid monitoring system, a real-time database is established to track the operational status of the power grid system in real time. Secondly, real-time state estimation is performed on the system to correct errors in uploading data information online. Finally, calculating power flow of the system to obtain the system power factor, and perform reactive power compensation on nodes with unqualified power factors to achieve an improvement in power factor. The correctness of the method was verified by simulation of a coal mine power grid example.