Abstract: NDT system based on machine vision for airplane protective grilling comprises hardware subsystem and software subsystem. Hardware subsystem comprises control system of precision movement, system of digital imaging, high-performance operation platform, and power-supply system, etc. Software subsystem comprises control software of detection, crack search of grilling image and location software. The system aims at structure characteristic of air-inlet protective grilling about airplane of the third generation. Through automatic detection and identification of crack and flaw in the protective grilling surface based on algorithm of intelligence detection, crack and abnormal area can be marked and stored, detection instability can be removed. The system not only improves accuracy rate of detection, but also shortens the test time and thus improves the detection efficiency.