Considering the problem of coarse microstructure and awful mirco-orientation distribution of TC4 titanium alloy welded-joint with high friability and low plasticity, we designed the post welding cyclic heat treatment between α+β and β-tansus temperature, and discussed the effect of different heat treatment process on the tissue morphology. The equiaxial alpha phase and lamellar alpha and transformed beta phase composition of the tri-modal microstructure was obtained. The study found that improving the cyclic times, occurrence of alpha phase could increase, and the ratio of length to diameter decreased.However, after five cycles some crystal orientation to meet the lamellar related to α Burger orientation relationship of abnormal growth, lammelar alpha rest staggered phase well-distributed, whereas equiaxed alpha phase is not conducive to improve the mechanical properties. When the clcyic times inceased, the more spherificated α phase appeared, and the length to diameter ratio reduced significantly, generally was less than 3. In addition, there were different kinds of small bars α phase around spherificated α phase. After four cyclic heat treatment, the product of strength and elongation of welded joint achieved 14441.17 MPa?%. The mechanical tests result showed that, after four times of cyclic heat treatment the plasticity of welded joint fracture are at maximum, compact size uniform dimples, have obvious ductile fracture characteristics. Almost at the same time, the yield strength and significantly increased, combined with analysis of EBSD, TEM test results, explain the causes of the phenomenon, and a detailed description of the changes in circulation process and spheroidizing mechanism.