In order to modify the steadystate resonance responses, a nonlinear parametric feedback control was proposed to reduce the amplitude of the response and to eliminate the saddlenode bifurcations that take place in the resonance responses.From the singularity theory approach, the nonlinear gain of the feedback control was determined by analyzing the bifurcation diagrams associated with the corresponding frequencyresponse equation.The illustrative examples show that the proposed nonlinear feedback is effective for controlling the primary resonance response.