To study the performance of wastewatertreatment mixer because of its large application in the rural environmental governance, based on CFD, using Fluent 6.3, wastewater treatment mixer with dome was simulated. At the same time, the velocity flow field distribution in the wastewater treatment pool was experimentally studied, and the fluid velocity at the different points of the pool was measured by using the velocity instrument. The velocity distribution graphs of the different sections in the wastewater treatment pool were drawn by software Excel, and the velocity distribution rule was analyzed. The same results were obtained by the numerical simulation and experiment. The fluid flow obviously transferred along the axial direction of wastewater-treatment mixer but little diffused along the radial direction, and fluid velocity symmetrical along the mixer axis. The results indicate that the wastewater-treatment mixer can guide flow in axial direction, and can reduce the effect of boundary of pool wall on the fluid in pool. 