Abstract: Taking the herbaceous vegetation under four typical forest types(Prunus armeniaca forest, Prunus armeniaca forest, Prunus armeniaca×Caragana korshinskii forests, Prunus armeniaca×Hippophae rhamnoides forests in Zhongzhuang small watershed of Pengyang in loess area of Southern Ningxia as research object, the root biomass and distribution characteristics of herbaceous roots in 0-30 cm soil layers of different woodlands were quantitatively analyzed by means of quadrat and root drilling method and Win RHIZO root analysis system, in order to reveal the distribution characteristics of herbaceous root system under different artificial forests in the loess region of south Ningxia, and to provide reference for ecological restoration and stand allocation in the study area.The results showed that the total biomass, total root length density and total root surface area density of the four forests showed that the mixed forest of Prunus armeniaca,Caragana korshinskii and Hippophae rhamnoides were larger than the pure forest of Prunus armeniaca and Prunus davidiana.The root parameters of each woodland were mainly distributed in 0-10 cm.With the increase of soil depth, the indexes showed a decreasing trend.The root length density and root surface area density of different diameter classes in 0-30 cm soil layer of four kinds of stands were basically the most widely distributed in 0-0.5 mm diameter class, and the proportion of fine roots in 0-2 mm diameter class was larger, and they basically showed a downward trend with the increase of root diameter.The root length density of different soil layers and diameter classes in each forest land was 0-0.5 mm＞0.5-1 mm＞1-2 mm＞2-3.5 mm＞3.5 mm.The root diameter.In conclusion, the proportion of root parameters in the soil surface of mixed forest was higher than that of pure forest, indicating that the mixed restoration model of stand played a positive role.