The fundamental theory of mixed form-finding method of membrane structures is discussed. The mixed form-finding method is developed on the basis of the force-density method. Some elements are force-density controlled, and the other elements are elastic controlled. The solutions of the former are obtained by use of the linear method, and the solutions of the latter are nonlinear. The corresponding computational programs are accomplished and the computations of practical examples are done. The coordinates of all points are in agreement with the ...