The main mechanism is a plastic film impervious partition earth dam leakage channels, with its larger tensile strength and elongation under pressure and adapt to the deformation of dam body; And non-woven fabric is a kind of high polymer chemical short fiber material, through needle stick or hot forming, has high tensile strength and extensibility, it combines with plastic film, not only increased the tensile strength and puncture resistance of plastic film, and because the non-woven fabric surface is rough, increasing the contact surface friction coefficient, is advantageous to the composite geomembrane, and the stability of the protective layer. At the same time, they have a good effect on bacteria and chemical erosion resistance, not afraid of acid, alkali, salt erosion, in use cases, long service life.