Gleeble-3500 thermal simulation compression testing machine was used to conduct thermal simulation compression on TA19 titanium alloy with the deformation temperatures of 820 ～ 980 ℃ and strain rates of 0. 01 ～ 10 s~(-1).The processing map of TA19 titanium alloy was established according to dynamic material model( DMM). Meanwhile,based on microstructure observation of TA19 titanium alloy,the influences of deformation parameters on processing diagram were revealed. The results show that the deformation parameters largely influence the power dissipation efficiency and flow instability. The power dissipation efficiency is relatively large at the strain rates of 0. 01 ～ 1 s~(-1). As the deformation temperature increases,the power dissipation efficiency first increases and then decreases,and gets the maximum value near 940 ℃ . Meanwhile,the flow instability includes two typical regions,including region I of( 820～ 900) ℃/( 0. 01 ～ 1) s~(-1) and region II of( 960 ～ 980) ℃/( 1 ～ 10) s~(-1). At 940 ℃,the more equiaxed α grain and higher temperature strengthen the recrystallization degree,so the power dissipation efficiency can be maximized.Adiabatic shear band,uncoordinated deformation between lamellar and equiaxed α phase,and sharp growth of β grain are the main causes of flow instability of TA19 titanium alloy.