Abstract: History and direction of future development of ultrasonic C-scan testing system were given simply in this paper. Products of several native systems and foreign systems were shown and described. Characteristics and application of five kinds of common ultrasonic C-scan testing systems such as planar scan system, revolving scan system, great non-planar scan system, revolving feed scan system for bars and tubes and portable scan system, were concluded, which would be helpful for choosing a system for specific application.