Abstract: Based on the field monitoring data, this paper deals with the hydrologic ecology of R. pseudoacacia plantation in the hilly loess region, northwestern Shanxi. The results show that the soil water conduction of the plantation was very poor and the available water content was very low during the growing season. The transpiration intensity (TRI) of the species was 0.1140g·g-1·h-1±0.0586 in growing season. The daily change in TRI was very significantly correlated with light intensity, but less with air temperature. Moreover, it was not significantly correlated with relative humidity. The water potential (WP) of the species was 1.759-MPa±0.457 in growing season. The daily change in WP was significantly correlated with air temperature, but less with relative humidity. Moreover, it was not significantly correlated with light intensity. The correlation between seasonal change in TRI and soil water content was not significant, but that between seasonal change in WP and the later proved significant. The correlation between the seasonal changes in TRI or in WP and the light intensity, the air temperature and the relative humidity was not significant. The water consumption through tree transpiration and the water consumption by the community evapotranspiration accounted for 16.3% and 68.0% of the precipitation, respectively, during the same period.