Abstract: The effects of three rolling temperature on the microstructures and mechanical properties of IMI550 alloy ϕ22 mm bars were studied.Experimental raw material having the same amount of rolling deformation,but rolling temperatures were T_β- 60℃,T_β- 25 ℃ and T_β+ 15 ℃.The results showed that the microstructure of IMI550 titanium bars rolling by T_β- 60 ℃,T_β-25 ℃ and T_β+ 15 ℃ were equiaxed microstructure,duplex microstructure and basketweave microstructure respectively.The room temperature tensile strength and 400 ℃ high temperature tensile strength with equiaxed microstructure,duplex microstructure and basketweave microstructure did not show significant difference,and plastic of equiaxed microstructure and duplex microstructure were also similar.The plastic of basketweave microstructure is relatively poor,but the creep properties is the best,duplex microstructure is the second,equiaxed microstructure is the worst.