In order to improve the identification accuracy of external diameter micrometer calibration, a lighting system suitable for industrial cameras was designed.The influence factor of lighting source was analyzed, the ring light source and dome light source were designed. The simulation experiment was carried out by using Tracepro. The uniformity was 72.2% and 74.6% under the ring light source and the dome light source respectively. The parameters of the lighting system were determined, and the lighting system was physically verified, by which the optimal lighting system was determined. The designed lighting system can clearly illuminate the indicator surface of the micrometer, which is conducive to capture high quality images and improve the accuracy of scale identification.