In order to explore the relationships between jujube tree transpiration and soil moisture in semi-arid loess hilly area, soil moisture and jujube tree sap flow were monitored for three consecutive years. Results showed that temporal and spatial variability of soil moisture were significant. Soil moisture increased with the increase of soil depth but its coefficient of variation decreased gradually in the vertical direction. According to the variation of soil moisture, soil depth was divided into three layers from top to bottom: soil moisture changing layer (0~2.6m), dried soil layer (2.6~6.0m) and soil moisture recovery layer (6.0~10.0m). Parameters of jujube tree sap flow were significantly different between growth period and dormant period, therefore, the growth period of jujube tree could be demarcated more accurately. The growth period divided based on sap flow characteristics lasted about 160d, which was similar to that determined by sprout and defoliation observation method, but it started and ended nearly 5d in advance. The increase of soil moisture led to forward of minimum values and delay of maximum values of jujube tree sap flow, the “lunch break” time was shortened, but the transpiration time was strongly prolonged, and vice versa. Jujube tree sap flow increased at the early growth stage, and the positive correlation between transpiration and soil moisture were significant at the middle and late growth stages.