A convergent iterative solution method for cables is formulated after solving the boundary problem with differential equation of a cable. By using the iterative solution, it is simple to determine the relation among the coordinate difference of cable-end position, cable tension and cable weight. The examples demonstrate that the present scheme for cable calculation can be as theoretically concise as required, and it is convenient to be used for analysing largely deformed complicated structures including cables or cable nets, and the present method makes it possible to solve the divergence problem of stress relieve of cables caused by employing some techniques such as Ernst Model for cables.