Abstract: This paper presents a comprehensive analysis of the characteristics of composite Geomembranes and their status quo of research; suggests a new and original method of conducting in a combined way decomposite and integral experiments on the material behaviour; establishes, through extensive research efforts, both on the decomposite and composite basis, a relationship of the integral mechanical and seepage control properties of composite geomembranes with their component materials as well as the bearing of the degree of compounding of the materials on the integral quality of the resultant geomembrane; discusses the testing technigues for composite geomembranes, reasoning out some research findings on adequate widths of test samples, which allow us to make clear a few things once being fuzzy in respect of previous testing procedures; and finally analyses the functional mechanism of composite Geomembranes in terms of their stress and seepage prevention performance.