Abstract: The design and development of an automatic ultrasonic inspection system for high-pressure gas cylinder group are introduced in this paper . The system is mainly used for automatic ultrasonic testing of the pipe of the high-pressure gas cylinder group without its disassembling. The inspection system consists of mobile module, wheel probe, intelligent ultrasonic excitation and data processing module. 100% full coverage scanning of the corrosion and defect inside the tube can be conducted by this system. After scanning, the C-scan images of defect distribution of the whole tube are generated. And the corrosion status and defect condition of the cylinder are displayed. The system is specially designed for on-site inspection of in-service high-pressure gas cylinders. The robot in the system can automatically move along the tube, automatically transmit, receive, process and store detection signals. The system has been tested and used on the actual high-pressure gas cylinder group. The sensitivity and resolution of the detection system meet the relevant national standards.