[Objective] The pull-out resistive properties of Ophiopogon japonicus and Indigofera amblyantha root were tested in order to provide guides for further research on the friction characteristics of the root soil interface.[Methods] Five levels of soil moisture content were designed to carry out single-root direct pull-out tests with vertical outward load.[Results] The maximum pull-out resistive force of the two plant root were both increased by nonlinear power function with root diameter as independent variable. Under the condition of constant soil bulk density

the maximum pull-out resistive force of root experienced an increases firstly and then declined as soil moisture content increased. The maximum pull-out resistive force of Indigofera amblyantha root was greater than that of Ophiopogon japonicus within a certain range of soil moisture content. While the maximum pull-out resistive force of Ophiopogon japonicus root was greater than that of Indigofera amblyantha under other conditions. Results also revealed that the pull-out resistive force of Ophiopogon japonicus root reached the maximum when the soil moisture content was close to 10.43%

while the pull-out resistive force of Indigofera amblyantha root reached the maximum when the soil moisture content was close to 13.00%.[Conclusion] Root diameter

soil moisture content and plants species have influences to some extent on the pull-out resistive force of root-soil interface.