The interfacial friction of composite geomembrane impermeable structures plays an important role in the safe and stable operation of an engineering project. In order to explore the interfacial friction characteristics of composite geomembrane-cushion, the indoor direct shear friction test, inclined plate test, indoor towing plate test and in situ test were carried out to statistically analyze the interfacial friction properties between two different geomembranes and cushions, including one piece of cloth & one piece of film, two pieces of cloth & one piece of film as the geomabranes, mortar and gravels as the cushions. The results show that for different cushion materials, the interfacial friction characteristics of sand and gravel cushion was better, its friction angle was 5.0 ° larger than that of mortar, and the cohesion was 4.2 kPa higher; for different types of composite geomembrane, the interfacial friction angle of two pieces of cloth & one piece of film was 3.4 ° larger than that of one piece of cloth & one piece of film, and the cohesion was 1.2 kPa higher. In different tests, the results of the direct shear test were closer to those of the inclined plate test; however the friction angle of the direct shear test was about 30 % smaller and the cohesion was about 4-6 kPa lower compared with the towing plate test. The results of the towing plate test were similar to those of the in situ test. Therefore, it is favorable to choose granular material as the cushion, and two pieces of cloth & one piece of film as the composite geomembrane in the design of the anti-seepage structure, and the towing plate test is a better choice for the evaluation of its performance.