Abstract: Effects of change of sediment concentration on lateral velocity distribution in U-Channel if important to theoretically perfect velocity distribution of sediment-laden flow and study on water and sediment movement in channel. Introducing index formula for velocity distribution, changes of the coefficient k, z of index formula when the sediment concentration is 500-1.12 kg/m3 in flow were investigated by the flume experiments in U-Channel, illustrating that lateral velocity of sediment-laden flow follows index formula of velocity distribution in U-Channel. In the case of s<300 g/m3, k, z increased linearly and slowly with sediment concentration increasing, and for s300 kg/m3, changes of k, z was from slowly increasing to sharply increasing. It is observed that when sediment concentration s 50 g/m3, the center of U-channel appeared core area, and the core area broadens as increasing of sediment concentration.