Abstract: To explore the influence of the guide vane form and configuration on axial flow fans, a two-stage axial flow fan with adjustable blades is selected in this study, and different guide vane schemes are constructed. The first option is to change all short guide vanes into long guide vanes; the second option is to change the hollow guide vanes to long guide vanes; the third option is to change all the blades to long guide vanes. FLUENT is used for the three-dimensional steady numerical simulation. The performance and internal flow characteristics under different schemes are examined and the optimal scheme is obtained. Simulated results show that scheme 3 that all guide vanes are replaced with long vanes achieves the best total pressure and efficiency at the design flow rate, which are increased by 3.8% and 1.8% respectively compared with the original one. The mixing of fluid between adjacent blades is reduced, and the flow fields in the first-stage static vanes area and the second-stage rotating blade area are improved. The total pressure rise coefficient of the second-stage rotating blades is greatly improved, and the overall working capacity of the fan is strengthened.