This paper proposes a new deformation control method based on the factor curves. Both Bars's global nonlinear deformation and Watt's space-time factor curves depend on some kinds of analytical expressions hence. The authors classify the factor curves and provide a unified deformation control method which is convenient for animation systems. By taking the factor curves as animation parameters, the new control method not only includes Bars's tapering and twisting operations but also Watt's factor curve control method. Animators can control the deformation effectively with the method.