. In order to enhance the mechanical properties of weld by using ultrasonic vibration, a new method of twin-arc TIG welding was developed. The welding will be completed by jointly using combined ultrasonic arc and ordinary DC arc technology. The ultrasonic arc was used for injecting ultrasound excitation into the molten pool to improve weld quality, and the DC arc was used as main heat source to increase deposition efficiency. The feasibility experiment of the welding system was done by using the steel 304. Metallographic analysis shows that the method can thin the microstructure of weld. The tensile testing under nature temperature indicates that the method can improve tensile properties of the weld effectively.