[Objective] The rainfall regimes and their effects on runoff and sediment yield in the small watershed of the upper reaches of Dawen River were studied, in order to provided a theoretical basis for the predicting and early warning of flood control and soil erosion in the mountainous and hilly areas of Central and Southern Shandong Province. [Methods] The Culai Mountain watershed in the upper reaches of the Dawen River was selected as the study area. K-means clustering and multiple linear regression analysis were employed to examine different types of rainfall and their impacts on sediment yield using rainfall, runoff, and sediment yield data from 2021 to 2023. [Results] The rainfall in this basin can be divided into four types, categorized as follows: type Ⅰ features small amounts of precipitation with low intensity, type Ⅱ features medium amounts of precipitation with moderate intensity, type Ⅲ features heavy amounts of precipitation with high intensity, and type Ⅳ features extra heavy amounts of precipitation with moderate intensity. Rainfall in types Ⅲ and Ⅳ was the main source of runoff and sediment yield in this basin. [Conclusion] The Culai Mountain watershed mainly experiences light rainfall with low intensity, yet the frequency of rainstorms remains relatively high. Affected by the mountainous terrain, the Ⅳ type rainfall was significant sources of regional floods and debris flows. Rainfall Precipitation amount is the primary influencing factor for runoff and sediment production in this basin.