In this paper, the dynamic mechanical properties and sensitivity of adiabatic shear banding of TC4 alloy having bimodal microstructures were invesgated using Split Hopkinson Bar.The bimodal microstructures with different volume fraction of transformed β matrix were obtained via different heat treatment. The results showed that the volume fraction of transformed β matrix increased with the increasing of solution temperature. Under dynamic compression experiments, the dynamic strength rised at first and went down latter as the volume fraction of transformed β matrix increased, and reaches its maximum value when the volume fraction of transformed β matrix was 80.7%. While the dynamic strain decreased with the increasing of volume fraction of transformed β matrix. Under forced shearing experiments, the sensitivity of adiabatic shear banding decreased at first and increased latter as the volume fraction of transformed β matrix increased, and reached its minimum value when the volume fraction of transformed β matrix was 80.7%. Besides, the sensitivity of adiabatic shear banding increased for the same microstructure with the increasing of impact velocity.