Abstract: The Hopkinson experiment system was used to do the dynamic tensile experiment of 800 MPa grade cold rolled dual phase steel (DP800). The strain rate was determined as 500, 1000 and 2250 s^-1 By comparing the experimental results, both the yield strength (R_p0.2) and the tensile strength (R_m) of the dual phase steel increase with strain rate in the exponential form. The plastic deformation at high strain rate leads to adiabatic temperature rise effect. The adiabatic temperature rise is 89℃ at the 2250 s^-1 strain rate. Based on the J-C (Johnson-Cook) model and Z-A (Zerilli-Armstrong) model, the constitutive model of the dual phase steel was researched. The quadratic polynomial of strain rate effect of the J-C model was modified. The average coefficient of determination increases from 0. 9228 to 0. 9886 by modifying the J-C model.