Abstract: There are two different ways for organic contaminants to transport through a composite liner.One is the transport through defect in geo-membranes,and the other is the diffusion through an intact composite liner.The accumulated contaminant mass through a liner was calculated with finite difference method and analytical method.The masses of the two ways were analyzed.For GCL(geo-synthetic clay liner)composite liner,diffusion is the main way and transport through defect can be defaulted.While for CCL(compacted clay liner)composite liner,both the two ways are important.GM+GCL+subsoil liner was very effective to retard the transport of organic contaminants.