Aiming at the present situation of smart substation clock synchronization system, this paper proposes the redundancy scheme of clock synchronization system based on IEEE1588. By analyzing the realization principle and characteristics of IEEE1588, a single clock scheme, double clock backup scheme and dual clock double extension scheme are proposed. The double clock backup scheme is emphasized, and the clock redundancy switching principle and process are detailed. At the same time, the double clock backup scheme in substation single network and dual network mode, and the effects of different network schemes on clock redundancy are studied.