Particles such as fish excretion and residual feed are easy to deposit in the pipeline and cause blockage, thus affecting the cleaning of water in aquaculture tank and causing adverse effects on fish.  Based on the numerical simulation of Lagrangian two-phase flow, the flow characteristics of particles in drainage piping are simulated, the suitable turbulence model and calculation scheme are calibrated based on the slurry pump pipe lifting test results, and the analysis and research are carried out accordingly. The flow characteristics of particles under different particle size, flow velocity and pipe diameter are analyzed. The results show that the SST K - ω turbulence model has high accuracy for the particle flow in the drainage piping. The influence of particle size on flow is very obvious. When the particles are small enough, the turbulence, drag and saffman force play a dominant role. When the particles reach a certain size, gravity becomes the main factor. For particle deposition, the influence of particle size is the largest, followed by inlet velocity, and the influence of pipe diameter is the least.