Abstract: To design the cover system or leachate collection system of a modern landfill, steady state solutions are usually used to analyze the maximum liquid head in the drainage system, but the increment procedure is rarely involved. Based on the extended Dupuit assumption, a computational solution is presented to calculate the transient liquid head. Compared with the results calculated by Ke Han (2005), the present method is shown to be more rational and accurate. By means of parameter analysis, it is found that in double drainage system the decrease of the permeability coefficient will cause the maximum liquid head to increase greatly, and the stable time will be longer. Reasonable drainage distance and increase of the slope will decrease the maximum liquid depth effectively. The application of the geocomposites will significantly reduce the maximum liquid depth of the drainage system.