Abstract: Suspended sediment movement is an important form of river sediment transport, and the existence of suspended sediment will also have an important impact on the properties of turbulent flow. In view of the complexity of suspended sediment movement, no consensus has been reached on the mechanism of water-sediment interaction. In this paper, the OpenFOAM two-phase flow model was used to simulate the equilibrium sediment transport under different working conditions, aiming to study the effects of suspended sediment particle size, density and concentration on turbulent flow characteristics, and to reveal the modulation mechanism of drag force, density gradient and particle collision on turbulent flow. The results show as follows: 1) With the increase of suspended particle size, the velocity of turbulent flow and particles decreases as a whole, and the velocity gradient in underflow area increases significantly. In the near-wall area, the sediment concentration gradient increases, the turbulence intensity decreases first and then increases, and the maximum value increases. 2) The increase of suspended particle density will lead to an increase in the average turbulent flow velocity, and the smaller the suspended particle density is, the more uniform the distribution of the concentration along the water depth, and the vice versa. 3) The increase of sand concentration will reduce the average turbulent flow velocity and turbulence intensity, and the higher the concentration, the more obvious the inhibition effect. 4) The increase of drag force will increase the turbulent flow rate and inhibit turbulent turbulence and sediment suspension. Suspended sediment density gradient inhibits both bottom velocity and top turbulence intensity. Particle collision reduces average velocity and significantly enhances turbulence, thus promoting sediment suspension.