Abstract: In order to study the influence of different blade incidence to contra-rotating auxiliary fan, numerical simulation are carried out at different working conditions by using Fluent. And simulation models are verified by experiment. Finally, efficiency and shaft power in different conditions are analyzed. Results show, if blade incidence is increased，the pressure and operating efficiency is also increased. Changing the front or behind Blade a same incidence, the difference between them is a little, but operating efficiency is more related to behind Blade incidence. Adjusting the Blade incidence will change the load of impeller, behind Blade incidence doesn’t have much affect on front, and the power of both stages will change when changing the front blade incidence.