Abstract: In view of problems of low measurement efficiency, high labour intensity and being influenced by subjective factors in manually calibrating coal mine electrical inspection instrument with digital display, an automatic inspection system for coal mine electrical inspection instrument with digital display was designed based on machine vision. The system controls power on of the instrument and a video to get booting process, and uses high lights statistics mode to identify key display frame of the electrical inspection instrument, uses template matching to complete automatic identification of the display image, and uses digit recognition with threading method to detect the measurement accuracy automaticly. Validity of the designed system is verified with experiment results from industrial prototype system.