Abstract: and near-α titanium alloys possess various good characteristics, including high specific strength,corrosion resistance ect. and are extensively utilized in many fields such as shipbuilding, aerospace, and atomic energy. The temperature field during titanium alloy welding significantly influences the microstructure of the welded joint, therefore affecting the mechanical properties of the component. In this paper, Gas Tungsten Arc Welding process（GTAW） was used to fabricate the butt joints of Ti-2Al-2.5Zr and Ti-4Al-2V alloys. The temperature field simulation of the welding process and the microstructure characterization and grain orientation analysis of the weld section were carried out. The results indicate that using zone welding process adjustment can obtain a relatively uniform temperature field. During the β phase transition, the cooling rate at each characteristic position is influenced by thermal transfer, thus exhibiting a certain order. From the Heat-affected zone to the Fusion zone,the microstructure of the weld seam transitions from equiaxed grains to elongated α’ phases and α layers, and the crystals exhibit a certain degree of variant selection, tending more towards two variant types: 60°/11 -20 and 60.83°/-1.377 -12377 0.359. During the β→αphase transition, the positions with lower cooling rates showed a decrease in the 60°/11 -2 0 and 60.83°/-1.377 -12.377 0.359 variants, while the 63.26°/-1055 -3 variants increased. The main two types of texture are 0001＜10 -10＞, and10 -10＜11 -20＞ plate texture.This study provides a scientific basis for improving the reliability of titanium alloy welded structures and the further application of titanium alloys in the field of high-end equipment manufacturing.