High temperature titanium alloy was prepared by selective laser melting technology, OM, SEM, XRD and mechanical tensile were used to study the effect of heat treatment on the microstructure and mechanical properties of high temperature titanium alloy. The results show that the metastable acicular martensite α 'is transformed into α phase and β phase after solid solution heat treatment. With the increase of solution temperature, the ratio of length to width of α phase decreases, and the grain boundary and phase boundary fracture occurs, and part of α phase breaks from strip to short rod or equiaxed. The tensile strength and yield strength of the formed alloy decrease gradually with the increase of heat treatment temperature, while the elongation increases gradually. Compared with the solid solution state, the second phase appears in the microstructure of the alloy after aging heat treatment, and the tensile strength and yield strength of the alloy at room temperature are obviously increased, while the elongation is decreased. The aging temperature has little effect on the tensile properties of the alloy at room temperature and high temperature. After the solution and aging heat treatment at 945 ℃/2h/AC and 700 ℃/8 h/AC, the alloy has good comprehensive mechanical properties.