Based on the necessary and sufficient conditions for existing of Hopf bifurcation, the ways to generate subharmonic bifurcation for single pendulum system is provided. Furthermore, this paper presents the application of Melnikov method in two-frequency drives single pendulum system. Therefore, the Hopf bifurcation and its conditions are discussed in detail and its application illustrates that this method solves many problems of Hopf bifurcation in multi-frequency drives single pendulum system.