Uniaxile tensile tests of auto-body steel sheet were performed at strain rate of 10-4 to 101s-1 and temperature of room temperature to 180°C. Strain rate and temperature sensitivity of flow stress were analyzed. It is found that the stress-strain curve is obviously heavily weighted on the temperature and strain rate. A new constitutive model was constructed and implemented into Abaqus/Explicit commercial software using user subroutine VUMAT. Verification of constitutive model shows that it has good agreement with experimental result.