The Qingshui River Basin in Ningxia is located in the arid and semi-arid transition area of the Loess Plateau. This paper selected the daily runoff and precipitation data of the Quanyanshan hydrological station and meteorological station in the Qingshui River Basin from 1989 to 2019, and used the Chapman-Maxwell method to divide the daily runoff time series of the basin. The result of base flow segmentation was applied to separate runoff events to further explore the response law of runoff events to precipitation. The results showed that: (1) The precipitation, runoff and base flow of the Qingshui River Basin in Ningxia showed an upward trend as a whole. The Mann-Kendall test showed there was no significant mutation time point. The precipitation with a daily rainfall of less than 10 mm showed an increasing trend. The annual precipitation was mainly distributed in May-September, accounting for 81.72%. (2) Based on the daily runoff time series, a total of 58 runoff events were isolated in the Qingshui River Basin in the past 30 years. Under drought conditions, the total amount of precipitation was significantly related to rainfall intensity. Under the influence of soil moisture and water storage, the runoff process under drought conditions was more sensitive to the precipitation response in the early stage of the event. In the rainy season, the total amount of precipitation and the precipitation intensity were the main factors influencing surface runoff. (3) The influence of soil moisture on the characteristics of runoff events had a threshold change. When the precipitation in the previous 10 days was less than 5 mm, the peak flow was sensitive to its response.