Abstract: The phase transformation characteristics of high strength steel SCr440 ( 0.40% C, 1.00% Cr) for automotive fasteners are studied by thermal simulation. From 850 °C by cooling rate ≤ 1℃ /s continuous cooling, the transformed structure is ferrite and pearlite, and bainite and martensite occur in structure with cooling rate reached 2 ℃/s, by cooling rate ≥7 °C/s the main structure in steel is martensite and bainite. The pearlitic transformation temperature is 550 ~700 °C during isothermal conditions, and bainitic transformation occurs when the transformation temperature decreased below 550 °C. Based on thermal simulation results, the Φ 18 mm SCr440 steel rod has been successfully rolled, and can be used to manufacture 10.9 grade automobile flange bolts by cold drawing to Φ 17 mm rod, then spheroidizing annealing at 700 ~ 760 °C and cold drawing to Φ15.7 mm rod.