Abstract: Effects of QT and QLT heat treatment on microstructure and properties of ZG14Ni3CrMoV cast steel were contrasted.The results show that the low temperature toughness of ZG14Ni3CrMoV cast steel is greatly improved by QLT process while strength of the cast steel meets the requirements and its plasticity is good; impact absorbing energy is 171 J at-80℃, and ductility transition temperature is reduced to-95℃; grain fineness and two phase structure mainly accounts for the improvement of the low temperature toughness of the two-phase region by QLT treatment.