In order to realize automatic detection of bearing dust cover in industrial field, the key technology of machine vision detection is studied, and a set of bearing dust cover detection is put forward based on machine vision. According to the characteristics of the bearing image, based on image filtering, a least square method is used to carry out circle fitting circle detection algorithm, the bearing detection and extraction of the ROI area are completed. The characteristics of the connected region are analyzed, then binary and morphological operations are carried out, and finally quantitatively processed and judged. The experimental results show that the method has good real-time performance and high detection accuracy, and can meet the industrial requirement of automatic detection of the bearing dust cover.