Both finite element method and cable numerical calculation have their limitations in calculation of main cable shape for self-anchored suspension bridge. This paper combined the characteristics of the two methods, and worked out the cable shape and internal force of self-anchored suspension bridge though iterative computation. Sanchaji Bridge, a self-anchored suspension bridge in Changsha city, its main cable shape was calculated by this method. Calculating results show that the real shape of main cable fit the results well and we should carefully calculate the length of girder compression which influences the unstressed length of main cable and the position of hangers. The calculating method adopted in Sanchaji Bridge offered a reference for design and construction for similar bridges.