Steel-plastic composite geogrid enjoys greater reinforcement effect than other types of geogrid due mainly to its special design and structure,such as deliberately roughed rib surface to enhance its surface roughness and friction coefficient.Hence,engaging force together with interface friction raises the reinforced soil's stability.Tests of pull-out on varied size of steel-plastics composite geogrid have been performed with copper tailing as filling soil,and interaction parameters of shearing intensity and pseudo-friction coefficient between geogrid and copper tailing are obtained.In addition,other influence factors have been discussed.