Geosynthetic Clay Liner (GCL), nowadays, represent a new technology that acceptance as a barrier system in sealing and waste landfills implementation. This paper investigates the undrained vertical capacity of strip footing on sand when a layer of GCL applied under it. Numerical solutions are obtained by small strain finite element analysis. In this analysis the GCL modeled as a layer of very loose permeable clay. Based on the analysis results, the effects of GCL that applied under strip footing on bearing capacity of strip footing will be demonstrated.