In order to reveal the response process of soil moisture of different vegetation types to rainfall of different intensities in Beijing mountain areas, Platycladus orientalis, Vitex negundo var, heterophylla shrubland, and native grassland were selected as the research objects. Based on the continuous observation data of rainfall and soil moisture from June to October 2022, the response characteristics of soil moisture to different rainfall events were analyzed. The results showed that: (1) during the observation period, the rainfall events in the research area were mainly consisted of light rain, with the total rainfall of the light rain event accounted for 14.78% of the total rainfall. The response depth of light rain events to soil moisture could reach 40-60 cm soil layer. The total rainfall of moderate rain, heavy rain and rainstorm events accounted for 85.52% of the total rainfall, the response depth of moderate rain, heavy rain, and rainstorm events could reach 60-80 cm soil layer. The replenishment effect of heavy rainfall was more obvious. The greater the rainfall, the deeper the soil layer that could be replenishment by rainfall, and the better the soil water replenishment effect. (2) The average soil water replenishment rate of the three vegetation was in the order of native grassland > Platycladus orientalis > Vitex negundo var, heterophylla shrubland, it indicated that rainfall had the best replenishment effect on native grassland. The active degree of soil layer had influence on soil moisture of vegetation. The more active the soil layer, the greater the fluctuation of soil moisture. The average soil moisture variation coefficient of the three vegetation types was in the order of native grassland > Vitex negundo var, heterophylla shrubland > Platycladus orientalis, while the average soil water storage capacity of the three vegetation types was in the order of Platycladus orientalis > native grassland > Vitex negundo var, heterophylla shrubland, indicating that Platycladus orientalis had the most stable soil moisture. (3) The soil moisture in each layer of the native grassland and the Vitex negundo var, heterophylla shrubland profile decreased gradually, while that of Platycladus orientalis increased, indicating that the distribution of soil moisture profile was influenced by vegetation types. The average maximum replenishment rate of Platycladus orientalis, Vitex negundo var, heterophylla shrubland, and native grassland occurred in the soil layer of 20-40 cm, indicating that rainfall had the most obvious replenishment effect on shallow soil moisture, and the replenishment effect on 0-40 cm soil moisture was better. The results further explained the law of water movement in the mountain ecosystem of Beijing, and provided a basis for the ecological environment construction in the fragile ecological zone prone to drought.