In this paper, we adopt servo-type strong machine to research the material mechanical properties of straight roots of Artemisia ordosica which is one of the dominant species in the coal mining subsidence area of Ordos. Results showed that the anti-tension force and the anti-fracture force of straight roots of Artemisia ordosica were positively correlated with the diameter of roots with a power function and both of the anti-fracture strength and the anti-fracture strength were negatively correlated with the root diameter with a power function in the 1～5 mm diameter range. Under the action of tension force and fracture force, the straight roots’ ultimate anti-tension elastic force was greater than the ultimate anti-fracture elastic force and its axial elastic deformation was smaller than the radial elastic deformation, it showed the characteristics of elasto-plastic deformation. The σ (stress)—ε (strain) curve under fracture force and tension force of the straight roots were concave and convex respectively, the ultimate strength decreased with the increase of root diameter, and the ultimate strain had no correlation with root diameter under these two kinds of force. The average anti-tension strength of the straight roots was greater than the average anti-fracture strength ((8.32±1.67)Mpa＞(5.39±0.85)MPa) in the 1～5 mm diameter range, it showed that the ability of the straight roots to resist axial tension elastic was better than the ability to resist radial fracture force.