Abstract: The thermal expansion curves of super cooled austenite under the dynamic continuous cooling condition of QP980 steel were measured by Gleeble-3500 thermal simulator. The phase transformation temperature was determined by tangent method, and the transformation type was determined by alloy phase method and hardness method. The dynamic continuous cooling transformation (CCT)curves of QP980 steel was obtained by using Origin software.The results show that when the cooling rate is less than 1 ℃/s, the transformation product at room temperature is a mixed structure of ferrite, pearlite and bainite.When the cooling rate is 3-10 ℃/s, with the increase of cooling rate, the amount of ferrite and pearlite decreases, while the amount of martensite increases.When the cooling rate is more than 10 ℃/s, the main microstructure is martensite.The test results can provide a theoretical basis for the production of QP980 steel.