Abstract: Microbubble generators have important applications in wastewater treatment. The Venturi gas-liquid two-phase blender has many excellent characteristics in the generation of microbubbles. In this paper, numerical simulation method was used to study the influence of geometric parameters of the Venturi-type blender on its blending performance. A single variable method was used to study the influence of the different shrinkage curves, the number of inlet holes, and the angles of expansion on the blending performance. By comparing the gas volume fraction of the outlet section, the pressure and turbulent kinetic energy variations along the axial of different models, the optimum geometric parameters of mixing performance were obtained. When studying the contraction curves, it was found that the gas-liquid blending performance of a straight line was the best among the five selected contraction curves. The number of intake holes was studied. The effects of one, two and four intake holes on the mixing performance were compared. It was found that the increase of the number of intake holes could improve the mixing efficiency within a certain range and the effect of the change in the expansion angle on the blending efficiency was found in this paper. In the studied range of 6 to 9°, with the increase of the expansion angle, the gas-liquid mixing efficiency increases significantly.