Abstract: The lamb wave induced longitudinal wave technology is presented for testing the adhesive bonded quality of rocket motor cladding. An ultrasonic C scan auto-testing system is developed. The testing systems constitution, operating principle, software design and hardware development are described. This system can display the adhesive bonded quality images and estimate the adhesive bonded quality. Its core is an industrial controlling computer. Now it has been put into operation. Its performance is stable, and the testing precision is high. It can test the rocket motor cladding with the salient points on the surface.