Abstract: Dynamic Hydrocyclone has many advantages such as high separation efficiency, low pressure loss, large work capacity and capacity changes in range. And it has been mostly studied for dust removal and oil-water separation in recent years. Based on the principle of Computational Fluid Dynamics, the inner flow field of Central Feed-in Dynamic Hydrocyclone is researched and analysed by using FLUENT of the hydrodynamics. Through the simulation, the results can accurately reflect the internal situation of the flow field, thus predict the separation effect and properties of the Dynamic Hydrocyclone, and guide the design of the hydrocyclone in structure. It provides a basis for optimal design of the Dynamic Hydrocyclone.