Based on the experimental data of size and concentration of suspended particle on Xiangxi River, the characters of size and concentration of suspended particle changed by the cascade hydropower stations were studied. The results showed that the size of suspended particulate matter (SPM) decreased from upstream to middle reaches, and changed from medium-large particulate matter to fine particulate matter. Without disturbance of hydropower stations, the decrease extent of size was more significant. No obvious differences were observed among the sizes of SPM at different sites from inlet to outlet of 26 typical cascade hydropower stations in the whole watershed. The concentration of total particulate matter increased at some special sites because of the disturbance of hydropower stations. It was showed that there was on obvious influence of hydropower stations on the concentration of particulate organic matter. The size and concentration of suspended particle diversification were related to flow velocity and water flow.