[Objective] Investigating rainfall regimes and their impact on sediment yield and loss in a watershed is scientifically significant for understanding the characteristics of rainfall regimes and the dynamics of soil erosion within the basin. [Methods] The Culai Mountain watershed in the upper reaches of the Dawen River was selected as the research subject. Utilizing rainfall, runoff, and sediment yield data from 2021 to 2023, this study employed K-means clustering and multiple linear regression analysis to examine different types of rainfall and their impacts on sediment yield. [Results] The rainfall of this basin can be divided into four regimes, categorized as follows: The features of Regime I are small amounts of precipitation with low intensity; the features of Regime II are middle amounts of precipitation with middle intensity; the features of Regime III are heavy amounts of precipitation with high intensity; the features of Regime IV are extra heavy amounts of precipitation with middle intensity. Regime III rainfall and Regime IV rainfall were the main sources of runoff and sediment yield in this basin. [Conclusion] The basin experienced predominantly light to heavy rain events with high frequency of heavy rain due to mountainous terrain. Regime IV rainfall significantly contributed to regional flood and debris flow hazards. Both Regime III rainfall and Regime IV rainfall were major contributors to sediment production in this basin, highlighting that precipitation was a key factor influencing sediment production. These findings provided a theoretical foundation for flood prediction, early warning systems for disaster mitigation, as well as soil erosion control measures in mountainous areas of south-central Shandong Province.