Abstract: Hardness-prediction mathematic models that calculate the hardness from chemical composition of steel and heat treatment conditions such as heating temperature and time as well as cooling rate were put forward by Maynier,modified and put into practice by Carsic.To verify the validity of the models,the Jominy bar tests were designed to quantitatively determine the relationship between the cooling rate and the hardness of two steels with different chemical compositions developed in Baosteel,and the comparison was made between the measured harnesses and the calculated ones by the models from the measured cooling rates.The results show that the models are good enough to predict the hardness of one steel,but not so good for another.It is,therefore,concluded that the validation and modification are necessary before the hardness-prediction models are used.