The stress-strain data from hot compression tests over a wide range of temperatures (1173–1473 K at an interval of 100 K) and strain rates (0.01, 0.1, 1 and 10 s-1) were conducted using Gleeble-1500D thermo-mechanical simulator. A modified Zerilli-Armstrong constitutive model was developed using the experimental data of 70Cr3Mo back-up roll steel. The predictable efficiency of this model was evaluated by correlation coefficient and the value was 0.9902.