As an alpine plant species native to the Qinghai-Tibet Plateau, Kengyilia hirsuta plays a crucial ecological role in maintaining the structural and functional stability of the ecosystem. Its specialized rhizosheath structure markedly improves the efficiency of water and nutrient uptake, thereby conferring enhanced drought tolerance and resilience in nutrient-deficient environments. Through metabolomic analysis, three differentially accumulated metabolites (arabinose, erythrose, and maltotriose) and soybean lecithin were identified as exogenous additives to evaluate their regulatory effects on root development in K. hirsuta. This study reveals that erythrose, maltotriose, and soybean lecithin induced an 18-23 % reduction in xylem vessel diameter, while the cortex-stele ratio remained stable. Notably, maltotriose treatment increased the total length of root by 34 % and elevated phytohormone levels (indole-3-acetic acid +27 %; cytokinins +19 %), yet exhibited no stimulatory effect on root hair proliferation. Intriguingly, all treatments resulted in thicker endodermal Casparian strips (1.4-2.1 x controls), suggesting reinforced ion selective filtration. Periodate-Schiff staining unveiled unique granular polysaccharide deposition patterns in root cell walls, indicative of specialized carbohydrate metabolism. Crucially, maltotriose treatment increased rhizosheath biomass by 41 % and soil adhesion capacity by 29 %, directly linking carbohydrate exudation to rhizosheath-mediated environmental adaptation. Our results demonstrate that specific sugars and phospholipids act as metabolic switches coordinating xylem remodeling and soil binding, with maltotriose emerging as a central regulator of K. hirsuta's root architectural plasticity and ecological competitiveness in desertified grasslands of the Qinghai-Tibet Plateau.