Abstract: Titanium alloys are often used to manufacture aircraft components such as aero engines, landing gears, and wing skeletons.The welds have to face complex environments such as high temperature and alternating load during service.The weld is the weak part of the component, and its common form of failure is fatigue fracture.Taking a 1.2 mm thick TC4 titanium alloy laser butt welding joint as the research object, the fatigue performance of the joint at 385℃was studied by changing the working width of the sample, the loading load, the vibration frequency and other conditions.The results show that the tensile strength of the joint is 885 MPa at 385℃.When the working width of the fatigue specimen is 3 mm, the maximum stress is 831.9 MPa, the minimum stress is 83.19 MPa and the vibration frequency is 10 Hz, the fatigue performance test is effective, the samples all fracture at the working section, and the fatigue life of the TC4 titanium alloy laser welding butt joint is 900863 times.