The invention discloses a power system time synchronization device based on a Beidou system. The power system time synchronization device comprises a device case and a clock unit. The input end of the clock unit is connected with a receiving unit, and the output end of the clock unit is connected with an output unit. The receiving unit comprises a Beidou module and a GPRS module, and the input end of the Beidou module and the input end of the GPRS module are connected with a receiving antenna. The output end of the Beidou module and the output end of the GPRS module are connected with a signal conditioning module. The clock unit comprises a core processor, the data input end of which is connected with an information reading module. The output end of the core processor is connected with an information exchange module, and the information exchange module is connected with the input end of the output unit. The core processor is also connected with a PPL phase-locked loop module, a man-machine interaction module, and a power supply module. The power system time synchronization device adopts a double-clock synchronization scheme adopting the Beidou and the GPS, and then the accurate and stable output of the internal time of the main clock formed by the above mentioned device is maintained at a nanosecond precision level.