Abstract: The settling and the separation of the tailings particles in fluid are studied. Firstly, the mechanical characteristics and the various force effects of the tailings particles in the fluid are analyzed. Secondly, the settling and the separation of the tailings particles in the Newtonian fluid are studied. Thirdly, the settling and separation of the tailings particles in the Bingham slurry are studied. Finally, the theoretical formula is derived and verified. The settling characteristics of the tailings particles in different fluids are determined, as well as the maximum size of the unsettled particles in the slurry flow, and the settling differential equation of spherical particles is deduced, as well as the formulas for the final settling velocity and the settling distance of particles, as well as the horizontal migration distance of particles. The theoretical formulas are verified.