Abstract: A water jet ultrasonic C-scan automatic imaging system with six degrees of freedom has been developed. The water jet coupling mode is used for ultrasonic detection and real-time imaging of large planar components, rotating bodies and complex curved surfaces. The six-degree-of-freedom industrial mechanical arm is used as the movement mechanism of clamping the transducer to enabling the profiling scanning of the complex shape components of the ultrasonic transducer; The real-time imaging of the workpiece is executed by using the tomography method; Emloying C# language as the programming environment, an ultrasonic C-scan imaging detection system with high integration and suitable for various working conditions was developed. The experimental verification demonstrates that the system is stable and reliable, with high detection accuracy and good repeatability.