Abstract: In order to reveal the mechanism about root reinforcing soil, roots tensile property of five common tree species in North China, Pinus tabulaeformis, Betula platyphylla, Larix gmelinii, Quercus mongolica and Ulmus pumila, were measured by laboratory tests, Results showed that a significant power relationship existed between ultimate tensile force and root diameter for all the selected trees. The root tensile strength of Pinus tabulaeformis and Betula platyphylla decreased with diameter increasing according to a power function, but it decreased for the rest species according to a logarithmic function. During the roots stretching, the sensitivity of root to tension fluctuated within a certain range. Betula platyphylla showed the strongest sensitivity, followed by Larix gmelinii, Ulmus pumila and Pinus tabulaeformis, Quercus mongolica had the lowest sensitivity on average. For the five trees species, the root stress-strain curve parameters were different with different diameters, but all of them showed the single-peak curves with elastic-plastic material characteristics. The parabolic function of third order can well reflect the basic characteristics of measured stress-strain curve. There are differences for the tensile property between different diameters and different species, but the underlying reason needs to be further investigated.