Abstract: The structure and the property of BT25Y titanium alloy by use of different temperatures and cooling rates for the solution treatment as well as thermal exposure were studied.The results show that solution treating at 950℃ is α+β two-phase region solution treating,the microstructure is constituted by isometric α crystal and layered α+β crystal,the rigidity reached the highest at 40 hours in thermal exposure;Solution treating at 990℃ is β single phase region solution treating,the microstructure is constituted by α+β phases which were decomposed from high temperature β phase,and the rigidity reached the lowest at 30 hours in thermal exposure,and then grows bigger with the time.