Abstract: The effect of cooling rate on DIFT (deformation induced ferrite transformation) microstructure evolution during continuously cooling was investigated for the vanadium microalloyed steel via thermo-simulator. The simulation results showed that the higher the cooling rate after large deformation, the finer the DIF (deformation induced ferrite) grains in specimens and, at the same cooling rate, the higher the vanadium content in the steel, the finer the DIF grains. However, at lower cooling rate, the higher the vanadium content, the more the carbonitride precipitates from vanadium, and no carbonitride precipitates are found in specimens at higher cooling rate.