The maximum range of active and passive laser range-gated detection system consists of the most far detection range of the visible/infrared system and the laser system. The furthest distance function of visible/infrared detector and the laser imaging were established respectively. The influence of the detector sensitivity, the transmission power, the laser emission angle and the atmospheric visibility on the maximum range was simulated. Two sets of range-gated system of 532 nm YAG laser and 860 nm solid-state laser were established. Simulation analysis system farthest distance is 11.2 km and 5.5 km respectively. 15.7 km, 10.9 km and 13 km targets are imaged using YAG laser. 1.3 km, 5.1 km and 6 km targets are imaged using solid-state laser. The most remote of the system is verified by comparing the distance between the targets. The experimental results show that the furthest distance from the theoretical calculation is basically consistent with the actual distance. The furthest distance function can reflect the actual performance of the system. It can be used as the basic reference for the evaluation of the system and it is an important reference for the design of the system.