Numerical simulations for the air-solid two-phase flow in a horizontal pipe with a diameter of 125 mm and a length of 10 m were carried out using the Computational Particle Fluid Dynamics (CPFD) method. The deposition characteristics of particles in the pipe were investigated at various inlet flow rates and velocities, and the effect of the auxiliary inlet with different structural parameters on the evacuation of particles in the pipe after the auxiliary inlet was added to the horizontal pipe was compared. The results show that when the volume fraction of particles in the tube is less than 0.6, the flow of particles is relatively stable, and when the volume fraction of particles is greater than 0.8, the particles are seriously deposited and easily form a blockage; the auxiliary air inlet speed is proportional to the effect at the same tilt angle; when the air inlet speed is constant, the auxiliary air inlet angle increases from 35° to 55°, the effect of auxiliary air inlet increases and then decreases, and the effect of auxiliary air inlet reaches its peak at around 45°. The study's findings have implications for long-distance particle transport in horizontal pipelines.