Abstract: In order to realize the time conformance of all devices in power grid, the time synchronization technique based on GPS/BD “dual mode” satellite common view system is proposed. The principle of CV system, the data processing algorithm and working mode are introduced in detail. It can realize time synchronization between primary reference clocks of power grid and local Coordinate Universal Time of National Time Service Center UTC(NTSC) using this technique.The intercomparison precision is better than 5ns using the GPS CV method, and it is better than 15ns using the BD CV method. The high precision, and high stability and highly reliable time unification are realized for the power grid.