In order to conduct a scientific and reasonable test of suspended sediment particle distribution at the hydrological section above the dam and collect better hydrological data,the variation trend of sediment in the basin was analyzed based on the sediment concentration data of 64 years from 1956 to 2019 and particle size data of 50 years from 1970 to 2019.The optimization and analysis of the test method for particle grading of suspended mass on dam stations affected by water conservancy projects are carried out,and a perfect test optimization scheme is formulated,which can ensure the representativeness and precision of hydrological data collection under the new water-sediment characteristics and reduce the test workload.