Abstract: Conduct research on the microstructure, mechanical properties, and heat treatment process of pure tantalum TIG joints. Industrial computed tomography (CT), OM, and SEM were used to characterize the microstructure of the joint, and microhardness tester and universal testing machine were used to test the hardness, tensile, and bending properties of the joint. The results indicate that welding parameters play a decisive role in the formation of the weld seam. Low current leads to incomplete penetration, while high current leads to burn through; Excessive speed results in incomplete penetration and undercutting, while excessive speed widens the heat affected zone. Selecting a welding current of 280 ~ 320 A and a speed of 150 ~ 180 mm/min as the process window, the maximum tensile strength of the joint under these parameters is 262 MPa, and the fracture surface exhibits ductile dimples. The fracture starts from the heat affected zone and extends along the softened zone near the fusion zone. On the basis of optimizing parameters, the influence of heat treatment temperature was studied, and it was found that with the increase of annealing temperature, the residual stress of the weld seam significantly decreased from 142.17 MPa to 10.69 MPa (1320 ℃), and the tensile strength decreased to 194 MPa due to grain coarsening. Based on the comprehensive stress relief effect and performance loss, 1320 ℃ is determined as the optimal heat treatment temperature. The actual structural components were welded using the preferred welding process, and after non-destructive testing and metallographic verification, there were no defects inside the joint, indicating good quality.