Abstract: Some new structural disfiguration,such as surface roughening, free volume increasing, interfacial disfiguration increasing in fibre and membrane, effective thickness decreasing, etc., is added to membrane of composite geomembrane during laminating process. The emergence of disfiguration is influenced by many factors. The higher proportion of LLDPE and more smooth surface of substrate with finer fibre are used in the membrane, the less structural disguration in membrane would be. It is easy to produce structural disfiguration for membrane with higher power during heating, lower velocity on production line and higher pressure during composition process.