Abstract:TC4 titanium alloys with different grain sizes were heated to 700℃ and compressed uniaxially using a Gleeble-1500D thermal mechanical simulator. Heating rates of 0, 10℃/s, 30℃/s, 50℃/s, 70℃/s were used for the heating process. The flow stress of the TC4 titanium alloys during the high temperature compression was investigated under the effects of the current by flow stress curves, SEM and TEM. It is found that the stress can be reduced from around 1000Mpa to below 600Mpa under the application of the current. Dynamic recrystallization occurs at a low current and the stress increases rapidly with the strain at first and reaches apeak value, it then decreases quickly and eventually become steady with the further increase of the strain. Dynamic recovery takes place at a high current and dynamic recrystallization is only found at some local areas. No stress peak is noticed with a high current and the maximum stress is below 400 Mpa. In addition, a higher current can promote a more complete phase transition from β to α. In conclusion, the flow stress of the TC4 titanium alloys can be affected simulteously by the current, dynamic recrystallization and phase transition and the current can facilitate dynamic recrystallization and phase transition, leading to decreasing flow stress.