The country has invested a large amount of manpower and material resources to control water pollution in Dianchi Lake in recent years. Although the water environment of Dianchi Lake has improved, there are still many problems. So far, the sewage interception and control systems has been built. In the entire system framework, in order to prevent backflow and large-scale overflow of the main canal, and to reduce the deposit of organic particles and silt in the intercepted rainwater on the main canal, it is crucial to carry out sand settling treatment and choose appropriate control methods to discard the rainwater in the rainwater main pipe before connecting to the main canal. Develop and design a cyclone hydraulic control switching well system of interception and abandon flow on this study, which controls the interception and abandon flow according to the water volume of the main canal. Using the three-dimensional design software SOLIDWORKS and simulation software FLUENT to construct a switching well model and simulate solid-liquid two-phase flow and studying the relationship between particle diameter, inlet flow rate, overflow pipe height, and particle removal rate. Optimal pool structure and corresponding operating conditions parameters of the switching well were finally obtained. At the same time, a practical survey was conducted on the site, and suitable sampling points for rainwater main channels were selected for rainwater particle size detection, some of the which were selected for parameter settings in the switching well simulation.