To overcome many shortcomings of the conventional LRG imaging system, such as need to know preset range delay and laser inner time delay. A kind of LRG imaging system based on the DSP is designed and realized, and its synchronization control technique is researched.The fast DSP controller is used to accomplish range measurement and range delay and to provide several nanoseconds gated pulse to gate ICCD camera.Range-gating and the precision image definition control can be realized effectively,and the targets＇range information and range-gating image are obtained without any preconditions.