This paper studies the nonlinear dynamics of a nonlinear energy harvester of magnetic levitation that uses electromagnetic induction to convert vibration into electrical energy under multifrequency excitation. The amplitudefrequency response of the energy harvester is investigated by varying the external frequency. The nonlinear equations of electromagneticmechanic coupling model are approximately analyzed by using the harmonic balance method and arclength method. Through changing the excitation frequency, the characteristics of the steadystate amplitudefrequency response containing two resonances are studied. The results show that the resonance peak of displacement amplitude frequency response under multifrequency excitation is decreased, but the bandwidth is increased with the increase of nonlinear coefficient. Moreover, the effects of the resistance, inductance and coupling coefficient are investigated to determine the influences of the intensity of energy acquisition and the bandwidth. In addition, the approximate analytic results are verified through direct numerical simulations of up sweep and down sweep.