In this study, a series of direct shear tests were conducted on two types of geomembrane-soil interfaces. Both textured and composite geomembranes were used to examine the shear strength. The strain softening behavior can be observed during shearing. Based on the experimental data, the shear strength parameters of (Composite) geomembrane-soil interfaces were calculated by the Mohr-Coulomb criterion. The results show that the textured geomembrane-soil interface exhibits greater shear strength than the composite geomembrane-soil interface and the sandy gravel provides greater shear strength than fine sand.