Abstract: At present, batch atomic layer deposition reactors have some disadvantages, such as uneven gas diffusion, low chamber utilization, the residual reaction of by-products, etc., which affect the quality of deposited films and reduce production efficiency. In view of the above problems, the simulation model of batch atomic layer deposition reactor is established by using Fluent software. Firstly, the effects of adding uniform gas baffles with different structural sizes to the reactor on gas velocity, concentration and diffusion time are analyzed; secondly, the influence of the distance between the racks on the gas velocity is analyzed. The results of Al₂O₃ film uniformity in the experiment and simulation are compared to verify the accuracy and reliability of the simulation model. It provides a reference for the improvement and optimization design of batch atomic layer deposition reactor.