Cable structures are widely used in practical construction due to its advantages of light weight, high strength which allow to build large span structures with nice view. The classical theory cable formulated from force balance equation of single cable, that is nonlinear; therefore, to determine displacement, deformation and tension forces of the cable we need to provide cable dip or horizontal tension force and use iteration calculation. This paper presents a new method for computation of flexible cable subjected to different loading pattern including concentrated force, distributed forces, pretension force, temperature variation. By application of the Gaussian Extreme Principle method, which developed by Prof. Drs. Ha Huy Cuong, to formulate and solve nonlinear equation system of cable structures, which ensured forces balancing as well as continuity of displacements and deformations of cable structures. This method allows for simultaneous determination of displacement, deformation and tension forces of cable structure without any other additional hypothesis, which is different from present cable theory. Numerical examples with simple, flexible cables subjected to different loadings have indicated the simplicity, accuracy and stability of the proposed method.