An intelligent transformer substation main/standby double-clock automatic switching time service system comprises a GPS (Global Positioning System) receiver and a receiver for Beidou satellite navigation and positioning system, wherein the GPS receiver and the receiver for the Beidou satellite navigation and positioning system are respectively connected with a PTP (Precision Time Protocol) time stamp unit, and the two PTP time stamps units are synchronously accessed into a local area network (LAN). The utility model has the advantages that dual-path PTP access respectively based on the GPS and a Beidou satellite source is achieved, and the reliability of the time service system is improved; time messages can be preferably selected in the time service system; the time service system can achieve automatic switching of an output clock; and the PTP time stamp units not only support a GPS time signal, but also support the input of a Beidou time signal.