To investigate the sediment transport characteristics of rotating flow in the desilting conduit of a trapezoidal desilting channel with a swirling flow generator, a combined method of model experiment and numerical simulation is adopted. The transport characteristics of sediment particles in the channel and the desilting tunnel under different inflow conditions are studied. High-speed imaging technology and numerical simulation results are used to analyze the variation patterns of particle trajectory, velocity, and acceleration under different inflow conditions. The results show that, through comparative validation of pressure, water surface profile, cavity shape, particle velocity, and swirl angle, the error between the numerical model and the experimental data is within a reasonable range, indicating the accuracy of the simulation. Under the flow rate of 30 m³/h, sediment particles entering the channel from the top sediment addition point are mainly influenced by the sediment-carrying capacity of the flow, with particle velocity maintained between 0.45 and 0.52 m/s, and acceleration fluctuating around 0~5 m/s² until reaching the channel bottom. Inside the desilting tunnel, sediment particles undergo vertical turbulence under the action of rotating flow, continuously colliding and rebounding against the walls, moving forward in a spiral pattern. At the 30 m³/h flow rate, particle velocity ranges between -1.8 and 1.8 m/s, exhibiting an M-shaped bimodal curve, and acceleration varies sharply due to the turbulent flow. Under different flow rates and particle sizes, sediment particles in the desilting tunnel exhibit different motion states and trends depending on inflow conditions and their own gravity. Particle velocity is proportional to the inflow rate, with a threshold observed at 70 m³/h. Sediment particle size is inversely proportional to average velocity and directly proportional to discharge time. By analyzing the forces acting on sediment particles in the desilting tunnel, an expression for the tangential flow velocity of particles in the swirling flow field is fitted, with the deviation between simulated and calculated regression values being less than 0.56%.