Plant population regeneration is of great importance for restoration of degraded ecosystems and preservation of biodiversity in the extreme arid region. The effects of soil environment on the characters and sprouting of propagative root of populus euphratica were investigated to elucidate the development mechanism of adventitious buds and root suckers. It was contributive to ameliorate the regeneration of the degraded riparian forest in the Northwest of China. Based on the investigation on soil profile and rhizotron in middle-aged and mature-aged Populus euphratica forest, the cloning root distribution characteristics, the root architecture, and the relationship between the sucker root and propagative root architecture were analyzed. Results show that: (1) with the increasing of the soil depth, the root length density (RLD) and root surface Area density (SAD) of fine root (d<2 mm) present the exponential function. (2) In different depths among 0-90 cm, the RLD and SAD of the fine root in middle-aged forest were significantly larger than the ones in mature-aged forest (P<0.05). However, in 70-90 cm (deeper layers) and 40-50 cm (shallower layers), the RLD and SAD of the middle-sized thick roots (5 mm<d<20 mm) and the thick roots (20 mm<d) in middle-aged forest, were significantly smaller than those in the mature-aged forest (P<0.05). (3) In the middle-aged forests, the root surface area, the root forks, the root fractal dimension, and the average branch angle were chosen as principal components in analyzing the root architecture. But the root volume, the root forks, and the average branch angle were chosen as principal components in mature-aged forest. The principal component analysis on the root order showed that the diameter class among 1-2 mm significantly influenced the SAD and the root volume. (4) There were no significant difference in the amount of the adventitious buds on cloning roots, the first-ordered lateral roots and branch angle between the two-age forests (P<0.05). (5) It was found that the amount of the adventitious bud on the second-ordered roots were 3-4 times more than that on the first-ordered roots by comparing the shoot bud on different root orders in the two-age forests. Based on the analyses on the trade-off of Populus euphratica root. Our result suggested that the fine roots (d<2 mm) would significantly affect the clone root architecture of Populus euphratica, and played an important role in the trade-off of Populus euphratica root function.