Abstract: The continuous cooling transformation(CCT) diagrams of austenite non-deformation and 50% compressively deformed at 950 ℃ were constructed on the Gleeble-1500 thermomechanical simulator and by means of a combined method of microhardness measurement for a microalloyed steel include V and Ti.Optical microscope and TEM were employed to investigate the influence of cooling rate,deformation process and microalloying elements on the transformation behavior and microstructure.The experimental results show that the deformation promotes the area of ferrite and pearlite move towards left,leading to the increase of critical cooling rate obtained ferrite plus pearlite.The deformation increases the transformation temperature of bainite and makes microstructure finer under high cooling rate.The stability of austenite is enhanced by the co-addition of V and Ti,which decreases transformation temperature and results the refinement of microstructure.