[Objective] Maximum flood peak flow is the decisive factor leading to flood disaster. The correlation between precipitation frequency, management level, and flood peak flow and flood disaster loss in a small watershed was studied to provide a scientific basis for soil and water conservation, disaster reduction, and prevention. [Methods] The water transfer benefits of soil and water conservation measures in two adjacent basins of Caijiamiao and Yehugou from 1981 to 2022 were analyzed by using both regression analysis and comparative analysis, as well as the effects of precipitation factors and soil and water conservation measures on flood peak flow. [Results] ① The benefit of water conservation measures in a small watershed increased with increasing management level, and decreased with increasing precipitation frequency. ② Annual maximum daily precipitation had a highly significant positive effect on the change of flood peak flow (p＜0.01), and the contribution rate coefficient was 0.707. Management level had a negative impact on the flood peak flow, and the contribution rate coefficient was -0.237. ③ The disaster loss intensity of 30-year flood peak flow (frequency of 3%) and 50-year flood peak flow (frequency of 2%) reached 1.74×10⁵ yuan/km² and 3.13×10⁶ yuan/km², respectively, with the latter value being 16.95 times greater than the former value. [Conclusion] The main factor affecting the change of flood peak flow was the annual maximum daily precipitation. Soil and water conservation measures had a significant impact on the reduction of flood peak flow. The higher the degree of watershed management, the more obvious the effect of reducing flood peak flow, and the greater the ability to reduce the economic loss of flood disasters.