[Objective] The effects of rainfall on soil and water loss of small watershed were analyzed in low mountains and hills area of Naning City in order to provide some theoretical basis for analyzing rainfall-runoff characteristics and managing comprehensively in low hill area. [Methods] Runoff and sediment data from 2015 to 2018, and 156 rainfall events were used in this study. Rainfall events were classified by using K-means clustering algorithm. The characteristics of different rainstorm patterns were analyzed by adopting LSD multiple comparison method. And multiple fitting regression equation of main indicators was established to explore runoff and sediment yield characteristics of small watershed under different rainfall conditions. [Results] ① The precipitation, I₃₀, and rainfall erosion force were the important influence factors of small watershed runoff and sedimentation characteristics. Among 156 flood events in the small watershed, the main characteristics were rainfall < 75 mm, I₃₀ <20 mm/h, the runoff coefficient <0.2, and the sediment concentration < 1 g/L. ② The rainfall events were classified into five rainstorm patterns as pattern Ⅰ (low P, low I₃₀), pattern Ⅱ (high P, medium I₃₀), pattern Ⅲ (medium P, low I₃₀), pattern Ⅳ (medium P, high I₃₀), pattern Ⅴ (low P, medium I₃₀). The frequency of pattern Ⅰ was the highest, while the frequency of pattern Ⅳ was the lowest. ③ The runoff and sediment yield of pattern Ⅱ and pattern Ⅳ were higher than that of other patterns, followed by pattern Ⅲ, and pattern Ⅰ and pattern Ⅴ were the least. There was no obvious difference among the runoff and sedimentation characteristics of pattern Ⅰ, pattern Ⅲ, and pattern Ⅴ. ④ The multiple fitting regression equation of modulus of sediment yield and peak discharge had the best simulating effect. The correlation coefficients (R²) was higher than 0.75 and passed the test of significance. The equation could be used to calculate various indexes quantitatively. [Conclusion] The precipitation, I₃₀, and rainfall erosion force were important influence factors to small watershed runoff and sedimentation characteristics. The rainfall characteristics of different rain patterns were significantly different. Pattern Ⅱ and pattern Ⅳ were the main rainfall pattern causing the runoff of small watersheds. Quantitative indicators could be calculated by multiple regression equation.