For the quality inspection of battery shell mounting holes and surfaces in the new energy & automotive industry, a detection system for battery box surface defects, dimensions, and positional accuracy relative to product processing reference points has been developed. Due to the large size of the product, the corresponding detection accuracy cannot be achieved when the camera covers the entire field of view, so a small field of view is used to measure the positional accuracy and dimensions of all battery shell mounting holes based on the established product coordinate system. After visual calibration, the pixel coordinate system of the camera is mapped to the axis system of the machine, thereby establishing the entire product coordinate system on the vision system, accurately measuring the positional accuracy and size information of each mounting hole. The presence of surface defects such as missing welding or excess welding on the battery shell surface is accurately judged based on image grayscale information.