In general methods of form- finding for cable and membrane structures, the connecting nodes between the tension structure and the supporting structure are regarded as fixed nodes. Displacement of these nodes on the supporting structure is not considered. In fact, the supports nodes should be regarded as elastic supports. The interaction between the tension structure and the elastic supports is considered in form- finding process. Finally, several examples are presented. Effects of the support stiffness on the form-finding results are discussed. Some helpful conclusions are given.