With the increasing span of cable-stayed bridges, the problems caused by the nonlinear characteristics of stay cables become more prominent. The accurate calculation of the linear shape of stay cables has become an important research subject. In the past, the linear parameters of stay cables were calculated by analytical method. But now, the finite element method is used as a computing equipment to build the finite element model of stay cable to adjust the unstressed cable length. Through the dichotomy iteration, the linear shape of the stay cable is accurately calculated, and its design parameters are extracted. And compared with the analytical calculation results, the results show that this method has a high accuracy in calculating the linear parameters of stay cables and can be applied to the design of cable-stayed bridges.