Abstract: The aero-engine C-ring seal is a metal elastic ring with large outward expansion deformation, and its tightness is related to the working efficiency of the engine. Aiming at the sealing performance detection problem in the production process, the light leakage detection platform based on the CMOS industrial camera seal ring weak light transmission environment is built. The image is processed and processed by the NI visualization software Vision Assistant, which can rm measure μm-level size and area of the light leakage area. The test results of the work piece sample show that the technology has high recognition accuracy and can greatly improve the detection efficiency, which provides a new effective way for the performance test of the C-ring seal.