Abstract: In order to make sure that the drift tube linac could work more stable and the transmission power could be fed into the linac better, the waveguide window of accelerating structure was designed and studied in this paper. The structure of waveguide window was calculated by CST, and the RF parameters were analyzed and optimized by improving the matching structure. Then the frequency bandwidth, electric field distribution and power loss were calculated by the simulation result. Besides, the thermal analysis of the RF window was carried out, and the flow rate of the cooling water was calculated by the formula. The result shows that the waveguide window can be applied to the 325 MHz acceleration structure.