Abstract: In order to analyze the influence of the gap between the rotary air preheater grid plate and the heat exchange component on the exhaust gas temperature, for a 330 MW power station boiler rotary air preheater, two models of equal resistance and equal flow velocity were established to calculate the exhaust gas temperature with different gaps between the grid plate and the component, while the exhaust gas temperatures of the air preheater with different gap values were obtained. Results showed that, when the gap value is less than 6 mm, the influence on exhaust gas temperature is slight, and when the gap is more than 12 mm, the influence on exhaust gas temperature is greater. Through a comparison between calculation results and actual operation parameters, the maximum relative deviation of exhaust gas temperature is 2.73%, which verifies the accuracy of the proposed calculation methods.