Abstract: A systematic study was conducted using the discrete element method combined with the volume of fluid (DEM−VOF) numerical simulation method to investigate the effects of particle parameters, inlet velocity and the ratio of distance (H) to diameter (D) on the multiphase flow characteristics and particle separation mechanisms in a spiral chute during the gravity separation process. The results show that the velocity of particles with high density and large particles increase due to their significant inertia under the influence of multiple physical fields, including gravity, centrifugal force, and fluid resistance. The average speeds of particles with densities of 1200 kg/m³ and 3000 kg/m³are 0.19 m/s and 0.34 m/s, respectively. This illustrates that the particles with a density of 1200 kg/m³increases by 78.94%. On the other hand, the average velocities of particles with a diameter of 4mm is 0.40m/s, which is 11.11% higher than that of particles with a diameter of 2 mm. In addition, these particles show a small turning radius. Thus, the particles are more inclined to flow towards the inner area of spiral chute. The fluid velocity, particle velocity, and particle flow track tend to stabilize when the multiphase flow in the spiral chute enteres the third circle. The increase in the inlet flow velocity enhances the fluid's driving force on particles and reduced interparticle interactions, thereby improving separation efficiency. Contact frequency of particle decreases by over 95% when the inlet velocity increases from 0.10m/s to 0.20m/s while the particle diameter and H/D ratio is fixed at 2mm and 0.4, respectively. Particle contact frequency increases within the first three circles and then decreases in the flow zone width of particle in the last two circles, which made the particles more concentrated. So the separation efficiency of particles is enhanced. In summary, the separation efficiency of complex particles improves when both the inlet flow velocity and H/D ratio increase.