Abstract: The Impact toughness of 10MnNiCrMoV steel, a new kind of ship steel was comprehensively studied. The result shows that the steel exhibits excellent ability to resist brittle fracture and is suitable for ship. The model formulation involving impact energy _VE_T、brittle transition temperature _VT_rE and experiment _VE_T/_VE_o=9+95/1+exp-0.05×(T-_VT_rE-2.5). The lowest impact energy at -40℃ of 10MnNiCrMoV can be determined under different working temperature with this model.