Abstract: The foreign matter in the micro-gel blood group test card seriously affects the clinical test results， so it must be strictly tested before it is distributed and boxed. At present， it mainly depends on manual lamp test， which has low detection efficiency and poor accuracy. In this paper， an intelligent detection system for micro-column gel foreign bodies is designed. In this system， the infrared LED light source with a specific wavelength band is designed to obtain the gel card image， and the improved Gaussian filtering algorithm and quadratic Gaussian difference algorithm for extracting the impurity characteristic information of the gel card image are studied and realized. The automatic control device for identification， tracking and rejection is designed， and the automatic separation of blood type test cards with foreign bodies is realized. Samples provided by Nevil Intelligent Technology Co.， Ltd. are used for testing， the detection accuracy of the proposed system is higher than 98%， and the minimum diameter of foreign bodies detected is 50 microns.

Key words: vision inspection system, microcolumn gel, improved Gaussian filtering