<p>Root system architecture has often been overlooked in plant research despite its critical role in plant adaptation to environmental conditions. This study focused on the root system architecture of the desert shrub <i>Reaumuria soongorica</i> in the Alxa steppe desert, Northwest China. Plant samples were collected during May–September 2019. Using excavation methods, <i>in situ</i> measurements, and root scanning techniques, we analyzed the root distribution, topology, and branching patterns of <i>R. soongorica</i> across an age sequence of 7–51 a. Additionally, we investigated the allometric relationships of root collar diameter with total coarse root length, biomass, and topological parameters. The results showed that the roots of <i>R. soongorica</i> were predominantly concentrated in shallow soil layers (10–50 cm), with lateral root branching and biomass allocation increasing with shrub age. The root topology exhibited a herringbone-like structure, with average topological and modified topological indices of 0.89 and 0.96, respectively, both of which adjusted with shrub age. The root system displayed a self-similar branching pattern, maintaining a constant cross-sectional area ratio of 1.13 before and after branching, deviating from the area-preserving rule. These adaptive traits allow <i>R. soongorica</i> to efficiently expand its nutrient acquisition zone, minimize internal competition, and optimize resource uptake from the upper soil layers. Furthermore, significant linear relationships were observed between log10-transformed root collar diameter and log10-transformed total coarse root length, biomass, and topological parameters. These findings advance non-destructive approaches for studying root characteristics and contribute to the development of root-related models. Besides, this study provides new insights into the adaptive strategies of <i>R. soongorica</i> under extreme drought conditions, offering valuable guidance for species selection and cultivation in desert restoration efforts.</p>