To investigate the grain growth behavior and its mathematical model of 45Cr14Ni14W2Mo heat-resistant stainless steel，grain growth experiments were conducted.A qualitative analysis of the microstructure morphology was performed，revealing that the grains of the heat-resistant stainless steel exhibited an equiaxed grain structure within the temperature range of 1 100 to 1 200 K，whereas the grains exhibited a mixed grain structure within the temperature range of 1 300 to 1 400 K. Additionally，a quantitative analysis of the average grain size was conducted， and the specific effects of holding time and temperature on the grain growth behavior of the heat-resistant stainless steel was thorough discussed.Based on the traditional Sellar and Beck model，a modified mathematical model for grain growth was proposed and calculated to characterize and predict the grain growth behavior of the heat-resistant stainless steel.The results show that the modified model exhibites significant advantages in prediction accuracy compared to the traditional model.