Abstract: Function with two undetermined coefficients was applied to characterize single pile displacement.Based on variational theory and minimum potential energy principle,analysis of pile group was deduced with the above function in order to get stiffness matrix of pile group.Displacement along pile length in pile group could be determined with the above stiffness matrix.Conclusion should be drawn after the comparison with other analysis methods that this method was as accurate as the other method,but less calculation was needed.The method have other advantage such as discretization of either soil or piles was not needed and solution procedure was rigorous for soil with stiffness increasing linearly with depth.