[Objective] In order to reveal the mechanism of soil reinforcement by roots, soil-root composites was selected to study the tribological properties between roots of Pinus tabulaeformis and soil by using the finite element program ANSYS 12.0.[Methods] Soil-root composites was regarded as the discrete model which was composed of root, soil and root-soil contact face. The root was analyzed by the linear elastic constitutive model, and the soil was analyzed by the elastic perfectly plastic constitutive model. The model parameters were calculated according to the triaxial compression test. The pulling out test of single root was simulated by nonlinear finite element in different burial depths and various root diameters. The relationship between friction and slip is analyzed and the curve was drawn. The results from numerical analysis were used to compare with the experimental data from the pulling out test.[Results] The results of the finite element numerical simulation were agree with the pulling out tests as the initial friction and peak friction increased with the increase of burial depth and root diameter.[Conclusion] The established finite element model can be used for the analysis of the root-soil friction characteristics, and it provides the basis for further numerical analysis.