Abstract: The single repetitive environment texture and poor illumination of the closed nuclear steam generator (SG) make the JP+1positioning of the inspection robot difficult, and it is difficult to determine the position of the heat transfer tube to be inspected during the operation. For this problem, a real-time robot localization method with high precision is proposed. The target detection algorithm was used to detect and sort the heat transfer tubes in the selected range in the video frame, and the initial reference number of the heat transfer tubes was set with reference to a small number of distinguishable points inside the SG in the initial frame. JP+2Based on the geometric constraint relationship between the distance between the same target in the front and rear frames and the distance between different targets in the frame, the heat transfer tube targets were tracked and dynamically sorted, so as to indirectly realize the precise positioning of the robot. The experimental results show that this method can well realize the high-precision positioning of the robot during the inspection process inside the SG simulation body, and can guide the robot to perform inspection tasks.