Abstract: Water consumption regularity of forest vegetation is the foundation and core of the studies about forest vegetation on hydrological processes influencing mechanism. In this study, relying on national forest ecosystem research station, the typical loess area of Caijiachuan Watershed of Jixian County, Shanxi Province of northern China was taken as the study area. In order to quantitative reveal the levels of transpiration and evaporation intensity and their relationship with environmental factors, the typical forest water consumption and related environmental factors were monitored in this region. Then the effects of forest vegetation structure on vegetation characteristics of water consumption were analyzed. In this study, the weighing method was used to measure the soil evaporation and thermal dissipation probe (TDP) was used to measure the sap鄄flow dynamics. Combing with the investigation of environmental factors, the data were analyzed. The results showed that: 1) surface vegetation and soil temperature had significant effects on soil evaporation; 2) there was a significant linear relationship between forest water consumption and soil moisture, rainfall, tree crown and tree age. In conclusion, the variation of soil moisture plays the main role in forest water consumption. Forest vegetation satisfies its water needs firstly while the soil moisture is low. To reduce the local forest water consumption, it is better to select the tree species according to their water needs and soil moisture before planting.