The invention discloses a two-end time synchronization triggering system and method applied to parameter measurement of a power transmission line. The system comprises a local synchronous triggering device and a remote synchronous triggering device, wherein a center control machine is connected with the local synchronous triggering device; the local synchronous triggering device and the remote synchronous triggering device are respectively connected with Beidou user machines through serial port communication; two Beidou user machines are connected with each other through satellite communication; GPS (Global Positioning System) time service modules are embedded into the local synchronous triggering device and the remote synchronous triggering device respectively. By adopting the two-end time synchronization triggering system and the method, an error between synchronous triggering signals transmitted from two places can be kept less than one microsecond, so that the requirement on measuring accuracy is met, and correct analysis of line parameters is ensured. An internal clock and a GPS synchronous signal work in a coordinated manner, so that a synchronous triggering signal can still be transmitted when a receiving blind area appears. An alarm is made when non-synchronous correction time surpasses a set value, so that a reference basis is provided for a technician to correctly judge and use the synchronous triggering device.