To solve the problem of water quality inspection in circulating aquaculture workshop under strong noise, low light and high humidity environment, this study proposes a water quality inspection system using three-dimensional lidar positioning technology. At the same time, based on multi-objective genetic algorithm, five main objectives are considered to solve the optimal path planning problem of the robot, including safety, distance, stability, travel duration and collision-free path, and the feasibility of the water quality inspection system is verified by experiments. The results show that when the inspection system cruises at 0.5 m/s, the maximum lateral deviation between the actual navigation path and the target path is 7.2 cm, the maximum longitudinal deviation is 6.3 cm, and the maximum heading deviation is 6.9 °. The improved path planning method based on multi-objective genetic algorithm reduces the path planning time by 31 % and 42 % respectively, and the obstacle collision rate by 15 % and 31 % respectively. When the path with the minimum time complexity is selected, the path planned by the proposed algorithm is more efficient. The research results can provide reference for the development of water quality inspection system in aquaculture workshop.