In order to reduce the wall temperature of the rotary detonation engine combustor， the active cooling structure of the ceramic matrix composite combustor was designed. The heat transfer characteristics of active cooling combustor structure were numerically simulated， and the wall temperature response and temperature distribution of the active cooling combustor were obtained. The model of the combustor active cooling structure was simplified， and the heat flux parameters at different wall temperatures obtained by simulating the rotating detonation wave were loaded on the cooling model， which improved the calculation efficiency of wall temperature simulation. The results show that the wall heat flux density in the combustor decreases with the increase of the wall temperature， and the average heat flux density in the diffusion zone is the highest； the active cooling structure of the ceramic matrix composite combustor can effectively reduce the temperature of the combustor wall. Under the same cooling flow rate， the cooling effect of the rectangular cooling section is better than that of the circular cooling section， which can reduce the temperature of the combustor wall to below 1 200 K； the highest temperature on the combustor wall is in the middle section of the combustor.