As the main dimensional component of the aircraft, the aircraft skin has the function of bearing loads and maintaining its aerodynamic performance. Compared with traditional skin defect detection methods only relying on visual inspection, the use of automated ultrasonic detection of internal defects and machine vision-based external defect detection methods have significant advantages such as high detection efficiency, high automation and strong consistency of detection results. According to the research progress of automatic detection of aircraft skin defects, the typical defect types of aircraft skin are introduced, and the application of automatic ultrasonic non-destructive testing technology and machine vision image processing technology in skin defect inspection is summarized respectively. The current problems and technical difficulties in the field of skin defect inspection are summarized, and the future development trend of aircraft skin automatic inspection is prospected.