Plant roots play an important role in improving slope stability. Root structure characteristics can reflect plant root function and ecological adaptation strategies, which is important for plant growth and development and ecological stability. In this study, simulated stony slopes were prepared by spraying in erosion channels. After 6 months of plant growth, whole-root excavation and Win-RHIZO root analyzer were combined to study the root architecture characteristics of 11 common slope protection plants under simulated slope conditions. Correlation analysis was used to analyze the relationships between plant root morphology and topological structure. The results showed that the biomass of 11 plant species showed significant differences, and the aboveground biomass ranging from 1.77 g to 23 g, the root biomass ranging from 1.1 g to 17.75 g. The root biomass of Alfalfa was the largest, while that of Caragana korshinskii was the smallest. The main roots of both were developed and only distributed in the down-slope direction. The root biomass, total number of roots, total number of basal roots, total root length, total root surface area, and total root volume of Astragalus adsurgens, Lespedeza bicolor, Amorpha fruticose, and Cerasus humilis were all large, and the roots were uniformly distributed in the up-slope and down-slope directions. The topological index of these four kinds of plants was between 0.53 and 0.61, which indicated a forked branch structure. The root topological index of Ziziphus jujuba var. spinosa (Bunge) Hu ex H.F.Chow. was 0.81, which was the largest compare to the other 10 plant species. The root system has strong soil fixation and slope protection ability, which could be used as the preferred plants for slope ecological restoration engineering. Both root surface area and root volume were linearly and positively correlated with root biomass (R²=0.68 and 0.80, respectively), while the root length, root surface area, total number of roots, and total number of basal roots were exponentially and negatively correlated with topological index (R²=0.82, 0.68, 0.87 and 0.86, respectively). The root structure types of the 11 plant species in this study were classified, and the results were as follows:Astragalus adsurgens, Amorpha fruticosa L., Rosa xanthina Lindl., Vitex negundo var. heterophylla (Franch.) Rehd. were R-type root structure due to the developed inclined root systems. Alfalfa, Caragana korshinskii Kom. and Ziziphus jujuba var. spinosa (Bunge) Hu ex H.F.Chow. were V-type root structure due to the obvious taproots and few horizontal roots and inclined roots. Prunus humilis Bunge was M-type root structure due to the numerous and dense root branches. Lespedeza bicolor Turcz., Rhus chinensis Mill. and Indigofera pseudotinctoria Matsum. were VH-type root structure due to the taproots and the roots were distributed horizontally in the soil surface. The results of the study can provide scientific basis and theoretical support for further study of plant root architecture.