A high precision synchronization method is proposed to realize the application in Shenguang Ⅱ between petawatt short pulse and main compression pulse. The short pulse from mode-locked laser and main trigger signal is locked by the and gate, which is the key to achieve synchronization between long pulse and short pulse in high-power petawatt system of inertial confinement fusion. In the and gate, the main laser control signal from the front-end system works as the trigger signal of the field programmable gate array (FPGA) circuit. The output picosecond pulse from mode-locked laser is transformed into electrical pulse as well as synchronized and widened, then sent into FPGA as a clock signal. The root mean square of 26.3 ps is obtained between the trigger signal of main laser gate pulses and the short pulse, and the proposed technology can effectively improve the stability of the synchronization system in the device.