The effect of β forging process on microstructure was studied by compressing test for Φ100 mm×150 mm TC17 titanium alloy bar.The results show that the height reduction and the deformation rate have a significant effect on the microstructure of TC17 titanium alloy.When the deformation rate is 0.1 mm/s,the grain boundary α phase is easily broken.And the larger the deformation is,the easier grain boundary α phases are to be globularized,which has been severely broken.The percent of globularized α phases is 80% at the height reduction of 80% and deformation rate of 0.1 mm/s.When the deformation rate is 2 mm/s,the β grains are prone to dynamic recrystallization.And the larger the deformation is,the higher the recrystallization volume fraction is.The recrystallization volume fraction of β grain is 50% at the height reduction of 80% and deformation rate of 2 mm/s.The grain boundary a phase can be globularized only in some strict conditions.The a phases are globularized only at the height reduction of 80% and deformation rate of 0.1 mm/s in this study.In addition,the amount of β grain recrystallization is more sensitive to the deformation rate than the height reduction.