The flow behavior of already forged Ti-46.2Al-2.5V-1.0Cr-0.3Ni alloy was investigated by the isothermal compression experiments. The direction of secondary hot deformation was taken to be vertical to the former forging axis. And the deformation activation energy was calculated. Specimens have three kinds of starting microstructures, i.e. as-forged, relief annealed and duplex. The true strain-stress curves show that the duplex microstructure has the lowest flow resistance, better steady-state flow behavior compared with other two microstructures. It is found that obtaining duplex microstructure makes the work hardening rate and the strain rate sensitivity increase. The duplex microstructure alloy has the lowest value.