Abstract: This paper presents an optical method to detect the flaw of chain slice.The information of flaw is detected from the change of intensity distribution of diffuse reflection light from the round edge slice illuminated by a He-Ne laser and recorded with a CCD camera.The theoretical width and maximum deviation of diffuse reflection light are calculated and the position confined condition of CCD camera is given.The experimental results show that the device is simple in structure and easy to operate and able to select the shortcoming slices rapidly and automatically.