[Objective] To explore the differences of roots biomechanical characteristics of different plants and the relationships between biomechanical characteristics. [Methods] Six common soil and water conservation shrub and herb plants on the Loess Plateau were selected. Their root morphology, chemical composition, and tensile properties, as well as their relationships, were systematically studied. [Results] 1) The root diameter（D） of the six plants was mainly fine roots（＜2 mm）. The root length density（RLD）, root surface area density（RSAD）, and root mass density（RMD） at different soil depths showed significant differences（p＜0.05）. The D, RLD, RSAD and RMD of Bothriochloa ischaemum were significantly different from those of the other five plants（p＜0.05）. 2) The average root tensile strength（T_r） of B. ischaemum was 6.83, 15.03, 30.15, 7.01 and 14.15 times of that of Carex tristachya, Artemisia gmelinii, Artemisia giraldii, Caragana korshinskii, and Sophora viciifolia, respectively. T_r decreased with the increase of D, following a power function or exponential function. Additionally, the contents of cellulose, lignin, hemicellulose and holocellulose were 13.43%-52.12%, 5.87%-26.31%, 1.01%-32.18% and 17.60%-51.8%, respectively. There were significant differences in the chemical compositions and diameters among the roots of different plants（p＜0.05）. 3) Plant root ultimate elongation(ε_max) and T_r were significantly positively correlated with hemicellulose content（p＜0.05）, and D was significantly negatively correlated with the chemical composition, ε_max and T_r（p＜0.05）. The total explanation of root morphology and chemical composition on root tensile resistance was 62.91%. [Conclusion] The results provide a scientific basis and theoretical guidance for the selection of native species and the internal mechanism of root-soil reinforcement for further ecological restoration on the Loess Plateau.