The invention discloses a method and device for high-precision time synchronization between adjacent devices in a power system, and the method comprises the steps: receiving and analyzing an externalIEEE 1588 message and a synchronous Ethernet message, and enabling a clock of a receiving end to synchronize the clock frequency and phase of an external clock source; and adjusting the sending end clock to keep synchronization with the clock frequency and the phase of the receiving end, and taking the sending end clock as a main clock of a next-level device to output an IEEE 1588 message and a synchronous Ethernet message at the same time. The requirement for high-precision time synchronization between adjacent devices is met, and the problem that an algorithm for achieving clock phase synchronization and frequency synchronization through software is complex is solved.