Abstract: Friction stir welding was used in hydrogen titanium alloy of 2 mm thick.Technology research was done about 0.1%and 0.4%hydrogen titanium alloy, respectively.Analysis of the microstructure-property of friction stir welding for hydrogen TC4 by SEM was conducted, and mechanical properties of the joints were tested or evaluated.Discussion of hydrogen titanium alloy welding performance was presented.Hydrogen TC4 joint was refined and hydrogen TC4 titanium alloy machining performance was improved significantly.