For the needs of quick and accurate inspection of assembly connection holes on skin, skeleton and otheraircraft parts, an on-machine vision inspection system was designed and developed. A specifically developed vision sensor is installed on the moving end of the five-axis CNC machine tool. According to the inspection path programed offline, themachine tool carried the vision sensor to each pre-determined position to grab image of each connection hole. The system software extracted and located the actual information of the connection holes from the image in a parallel processing way. An error evaluation procedure was developed in the software to finally complete the non-contact rapid connection hole inspection. The work flow, software and hardware architecture of the system were introduced. The key techniques such as the calibration of system parameters, the generation of NC inspection codes and the error evaluation method were discussed in detail. The inspection results of actual aircraft parts demonstrate that the efficiency of the developed on-machine vision inspection system is as high as 5s/hole, and the precision is about 0.01mm. It well satisfies the inspection requirements of large quantity of small size connection holes distributed on complex surfaces.