Abstract: A set of underwater range-gated imaging system based on laser illumination was developed for the detection of underwater targets. This system used 532 nm Nd:YAG laser as illumination source whose maximum pulse power was 400 mJ, and used 10242024 ICCD as range-gated and imaging device. The minimal gate length of the system was 3 ns. A digital pulse producer DG535 was used as an accurate time-lapse device to synchronize the laser with ICCD range gate to realize the systems range-gated function. An underwater target detection experiment was carried out in a reservoir with this system. The result of the experiment indicated that the largest target recognition depth is 6.5 times the attenuation length of water for this system and the target in 8 times the attenuation length of water could be found with this system.