Based on numerical simulations and flume experiments, the processes of sedimentation of suspended solids and resuspension of sediments in the region downstream of a sewage outlet in a river were analyzed at three velocity ratios(R=4. 5, 7. 2, and 9. 9, where R is the ratio of discharge velocity at the sewage outlet to the flow velocity in the river). Results show that the relative turbulence intensity and the area of the pollution zone increased with the velocity ratio; this also resulted in significant sedimentation of suspended solids and resuspension of sediments in the river. At the three velocity ratios, the sedimentation fluxes of suspended solids through the bottom horizontal plane have similar distributions: first increasing and then reaching respective stable values; and the total fluxes of suspended solids increased with the velocity ratio. At a low velocity ratio(R=4. 5), the resuspension fluxes of suspended solids increased slowly due to the existence of a critical incipient velocity(corresponding to R=5. 8), while at the medium velocity ratio(R=7. 2)and high velocity ratio(R=9. 9), the resuspension fluxes increased rapidly. As a result, the discharge velocity of the sewage significantly affected the sedimentation of suspended solids and resuspension of sediments in the region downstream of the outlet.