Abstract: Abstract: To improve the yield and benefit of aquaculture, intensive aquaculture model with high stocking density and high feeding amount is generally adopted for pond culture. However, the residual bait and manure, chemicals, antibiotics and other pollutants generated during aquaculture into the water, causing great pollution of the surrounding environment, and even caused lake degradation, marine red tide and other adverse environmental pollution phenomena, resulting in a sharp decline in biodiversity, which has become a bottleneck limiting the sustainable development of China's aquaculture industry. Therefore, the pond aquaculture tailwater treatment equipment with small size, low cost and high efficiency is the key technology to be urgently solved in the aquaculture field. Cyclone separator is a centrifugal separation device, has the advantages of no energy consumption, small size, convenient assembly and disassembly, and is widely used in petrochemical industry, water sand separation, industrial sewage treatment and other fields. In order to apply multi-stage cyclone separation technology to purify pond aquaculture tailwater and solve the problems of short hydraulic retention time and low separation efficiency of cyclone separator, the series cyclone separator was designed. According to the wastewater characteristics of Penaeus vannamei cultured in ponds and referring to the structural parameters of industrial standard 150 cyclone separator. Based on Eulerian-Lagrangian method, combined with the Reynolds Stress Turbulence Model and the Discrete Phase (DPM) Model, a three-dimensional numerical simulation model of two-phase flow was established. On the basis of comparing the experimental data to verify the effectiveness of the numerical method and grid independence analysis, the influence mechanisms of inlet flow rate, cone angle, particle size and density on flow field characteristics and separation efficiency were analyzed, and a solid-liquid separation technology for pond aquaculture wastewater by multi-stage "swirl + filtration" was proposed. The results show that, at the same flow rate, the separation efficiency of the series cyclone separator is higher than the industrial standard 150 cyclone separator. With the increase of the inlet flow rate in a certain range, the tangential velocity, axial velocity, shunt ratio, pressure drop and turbulence intensity increase in flow fields of the series cyclone separator, and the separation efficiency of particles with size of 75 μm increases significantly, while the changes of 5 μm particles are not significant. When the flow rate is higher than 23.91 m3/h, the increase of separation efficiency is significantly reduced; With the cone angle of the cyclone separator decreases, the water flow resistance, pressure drop and split ratio decrease, which is helpful to increase the residence time of particles in the swirl zones and improve the separation efficiency. With the increase of particle density and size, the separation efficiency of the cyclone separator increases, the sediments with particle size of 75 μm reaches 80%, and suspensions with the same particle sizes are about 60%. However, the separation efficiencies of particles with 5 μm particle size are not significantly different, both are less than 30%. The research can provide a theoretical basis for the optimal design of cyclone separator and its application in pond aquaculture tailwater.