Abstract: Berylium copper welder workpiece is the cladding material of nuclear fusion reactors, working under bad condition, and its welding quality needs to be inspected. In order to realize the inspection of the quality of the berylium copper welding, firstly the theoretical analysis has been done for the feasibility of ultrasonic testing. Special ultrasonic probes have been designed and special sensitivity test block was designed and processed. The inspection method and inspection technology have been studied. Through the comparison of the experimental data of the American counterparts, the correctness of the quality ultrasonic inspection method for berylium copper welding is verified. This method is versatile and applicable in other workpieces.