The effect of B/Y composite trace addition on the solidification process and microstructure of high temperature titanium alloy was studied. The microstructure evolution process of high temperature titanium alloy at different deformation temperatures is analyzed. The tensile properties at room temperature and 650 ℃ were tested. The results show that the micro-composite addition of B/Y leads to component undercooling during the solidification of high temperature titanium alloys, forming chain-like TiB reinforcing phases wrapped in β grain boundaries and rare earth oxide particles dispersed in the grain boundaries and within the grains. The original β grains are refined, the movement of β grains boundaries is inhibited, and the aspect ratio of the α lamella precipitated in the crystal is reduced. After single step axial deformation at different temperatures, there are inhomogeneous microstructures at different positions of the hightemperature titanium alloy cake blank. The TiB reinforcement phase promotes the spheroidization of the secondary α phase. The results of mechanical properties and the analysis of the tensile properties show that the deformed alloy in the twophase zone has a good strong plastic matching, and the tensile strength of the high temperature titanium alloy at 650 ℃ is significantly improved after the B/Y composite addition.