Abstract: The relationship between fine roots distribution of Populus simonii and Caragana korshinkii and soil water in the wind-water erosion crisscross region of the Loess Plateau were studied based on 2-year field positioning observation.The following conclusions can be drawn from this paper: 1) The fine root area density(FRAD) of Populus simonii and Caragana korshinkii declined with the increasing of soil depth,the proportion of fine roots in 0-100 cm soil layer was 63% and 95% of the whole profile,respectively.2) There are closing relationship between soil water in profile and fine roots distribution,the soil water characteristics in profile was similar between Populus simonii and Caragana korshinkii stands.According to the soil water variation,the soil profile can be divided into 3 layers: 0-50 cm was fast change layer,50-200 cm was slow change layer and gradually attenuation layer below 200 cm.3) Total ET in Populus simonii stand was close to Caragana korshinkii stand during 2year,and which almost equaled to rainfall during the same period.4) Most of fine roots of Populus simonii and Caragana korshinkii concentrated in shallow layer of soil,because the upper soil was frequently recharged by rainfall in this region.These results will provide an important theoretical basis to protection forest construction in the wind-water erosion crisscross region.