Focusing on problem of complex ultrasonic probe movement on curved missile surface during automatic detection, a detection method using the known parameters by calculation and presetting motion path was proposed. After analysis of the structure of missile components, the spray coupled method was used not to impact on the movement when the component surface had a greater change. Since the components consist of hollow and solid parts, so the movement under a variety of structural components based on detection should be analyzed when path calculation. With this method, the time spent on ultrasonic ranging and ultrasonic probe position adjustment was reduced, and the efficiency of the automatic detection was improved.