To solve the navigation and positioning problem of the underwater net inspection robot, a positioning method of the robot based on the laser array is proposed by using the advantages of high precision and low interference of the laser sensor in the underwater short-range range. Based on the physical model of the cage, by establishing an a priori map of the cage code and simulating the operation of the robot in the gazebo simulation environment, the relative sailing distance and yaw angle of the robot to the netting are calculated from the laser ranging information, and the average error is 3.72% at the distance of 0.4 m, 8.15% at the distance of 0.08 m, and 19.18% at the deflection of 0.14 rad. The error in the positioning of the 8×6 net grid is 0 mesh, It shows that this method can meet the positioning requirements of the robot in the aquaculture cage under the non inertial frame. The results show that this method can provide a reference for the further study of the underwater net inspection robot positioning in deep-sea aquaculture cages.