Because of the complex flow phenomenon in the mixing equipment, the design of the mixing equipment depends on the actual operation experience of the engineers. With the increasing application of numerical simulation technology in various fields, the application of numerical simulation technology to the design of mixing equipment has a great advantage over the traditional experience design method. In this paper, the three-dimensional flow field of the water treatment agitator is simulated by two modeling methods, and the characteristics of the flow field are compared and analyzed, which will provide some reference for the optimization design of the water treatment process.