Tensile strength is one of the plant root traits most commonly used by engineers when modeling slope stability. In order to establish an integrated mechanical model of root tensile strength, specimens of root in North China of different lengths and varied tensile rates were carried out for tensile test. Analysis of test data showed that all values of root tensile strength were observed by normal inspection; from a mathematic point of view, a distinction was made between fine and thin roots of four tree species by using cluster analysis; both root length and tree species had significant effects on tensile strength, while tensile rates had no significant effects on tensile strength. Moreover, based on theoretical derivation and data analysis, the synthesis mechanical model of tree singleroot tensile strength was established and its parameters were solved out. It had researched mechanism of singleroot tensile strength, which can provide important reference value for the establishment of slope stability model.