To understand the variation of soil water content in loess slope due to rainfall infiltration, the soil water content and rainfall were monitored on a typical natural loess slope in Baota Mountain of Yan'an City, Shaanxi Province. The monitoring results showed that there was temporal hysteresis and spatial difference in the responses of soil water content to rainfall infiltration. The impact depth of rainfall infiltration was less than 1.0 m when the daily rainfall was 10 mm or the 10-day cumulative rainfall reached 70 mm. When the daily rainfall was 50 mm or the 10-day cumulative rainfall reached 140 mm, the impact depth was less than 2.0 m. The rate of rainfall infiltration was 0.04 m/h at the shallow depth of 0.2 m and it decreased to 0.033 m/h from the depth of 0.2 m to 1.0 m when the cumulative rainfall reached to 10.4 mm per hour at the study area. The rainfall infiltration rate decreased with the increase of depth.