Abstract: Synchronization of laser pulse and voltage pulse is important in laser-triggered surface flashover experiments. Of the laser-triggered surface flashover facilities, a high precision laser trigger system was built. A single/double harmonic, with wavelengths of 1 064/532 nm, Q-switched Nd:YAG laser was used to trigger the surface flashover. The delay time and jitter of Marx generator’s trigger input and output, Marx generator input and output, laser input and output were respectively measured. A self-made digital delay and pulse generator was used in the trigger system. The digital delay/pulse generator controls Marx generator’s trigger and the Xe lamp of laser. The Q-switch of laser was controlled by the Marx gneerator’s output. Based on the result of the delay time and the time sequence