The theory of geometrical nonlinear analysis is introduced. The sag effect is considered by the multiple-straight truss elements. The unstress length which is modeled the tension force of cable is figured out. Three kind of positions where the new elements are activated on are offered: tangent to old elements, parallel to old elements and original model coordinate, the method of parallel to old elements is used in the construction stages analysis and the method of original model coordinate is used in the construction control analysis. The purpose of construction control analysis for pretensioned structure in this paper is that the architectural configuration should be satisfied after construction control analysis is finished. The procedure of construction control analysis for pretensioned structure is summarized. The computational accuracy and the effectiveness are proven by the example of the cantilever beam with cables.