Abstract: Thirty-six river basins, where the data of measured grain size of sediment are available, were chosen for an analysis on relationships between grain size of sediment and rainfall features in the middle reaches of the Yellow River. These basins fall into 5 types of different physio-geographical environments. Annual average rainfall, unevenness, seasonality and yearly variation of rainfall were taken as the indices of rainfall to relate to grain size of sediment. It was shown that good linear positive multi-relationships exist between grain size of sediment and seasonal and annual variation of rainfall when taking the different types of basin as perameters, but simple non-linear relationships between grain size of sediment and annual average rainfall and unevenness of rainfall. Vegetation, surface material and landform exert an important control on the relationships between grain size of sediment and rainfall features. Different slope and positions of curves were observed in the relationships between grain size of sediment and seasonal and annual variation of rainfall for different types of river basins. The slope of curve decreases and the position moves down subsequently from the basins of windy sand, sandy loess and heavily weathered siltstone and mudstone to those of loess and clayey loess. The different positions were also observed in the relationships between grain size of sediment and annual average rainfall and unevenness of rainfall for different types of river basins. From the upper to the lower of the curve the type of river basin changes from the basins covered by windy sand, sandy loess or heavily weathered siltstone and mudstone to those of loess and clayey loess subsequently.