After the packaging process, integrated circuit (IC) chips must be strictly tested to ensure the quality of products. Chip appearance inspection is an essential and important link, which directly affects the quality of IC products and the smooth progress of subsequent production links. There are three methods of appearance inspection: one is the traditional manual inspection method, which mainly depends on visual inspection and manual sub inspection. It has low reliability, low inspection efficiency, high labor intensity, omissions in inspection defects, and can not adapt to mass production and manufacturing; The second is the detection method based on laser measurement technology, which has high hardware requirements, high cost, high equipment failure rate and difficult maintenance; The third is the detection method based on machine vision. Because the detection system hardware is easy to integrate and realize, the detection speed is fast, the detection accuracy is high, and the use and maintenance is relatively simple, this method is more and more widely used in the field of chip appearance detection, which is a development trend of IC chip appearance detection.