The primary harmonic of a self-sustained nonlinear electromechanical coupled system is computed by using the harmonic balance method. Based on the theory of Floquet, the stability of primary harmonic was analyzed. Also, the exact linearization controller for this electromechanical coupled system was designed based on the theory of differential geometry. The research results show that the amplitude of the harmonic solutions for this electromechanical system increase along with the decreasing of frequency, and the amplitude reached the maximum when the frequency reaches the main frequency. Meanwhile, the amplitude will jump and the system will emerge chaos. Furthermore, the relative degree of the system is 4 after adding a feedback controller to this system, and so that the control system can be linearized at all the state points. Finally, the numerical simulation results demonstrate the effectiveness and realizableness of the proposed method.