Taking the 1~5 mm straight roots of Caragana microphylla as the research object, the effects of 50 times of loading (70% of the ultimate tensile-shear combined force of the test roots) on the mechanical properties were studied using TY 8000 servo-type strength machine. The results showed that the slope of the ultimate force-radial displacement curve of the test roots was larger than that of the control after 50 times of loading, and the ultimate tensile-shear combined force and strength of the test roots were significantly higher than thsoe of the control roots (p<0.05). After repeated loading, both the function relationship between the combined tensile and shear forces and diameters and the function relationship between the combined tensile and shear strength and diameters of the test roots were similar to those of the control, but still showed a positive and a negative power function correlation, respectively. With the increase of root diameters from 1~2 mm to 4~5 mm, the ultimate tensile-shear combined force of test roots increased from 1.26 to 1.34 times of the control. With the increase of loading times, the increment of radial displacement of test root decreased.