Abstract: Aiming at how to improve the operation performance of portable axial flow fan, through the optimization design of its structure, the effects of the number of blades of the rotor components and the change of the blade mounting angle on the matching of the impeller and the guide vane were mainly investigated. Based on the SST k-ω turbulence model, numerical simulations were applied to investigate its internal flow characteristics, and the reliability was verified by experiments. The results show that the blade mounting angle has a large influence on the performance of axial fan, while the number of blades has a relatively small effect. By comparing and analyzing the internal flow characteristics between different models, the blade mounting angle and blade number suitable for portable axial flow fan are determined. It is found that the development of tip leakage vortex has different effects on the near guide vane with the change of the installation angle and induces fluid disturbance at the junction region of the impeller and the guide vanes, which affects the matching of the impeller and the guide vanes. The maximum turbulent kinetic energy exists at the inlet of the impeller blades, and the top of the leaf region is greater than that in the root of the leaf region due to leaf top leakage. The analysis of the structural optimization and internal flow characteristics of axial fans has certain guiding significance for the design of axial fans.