Abstract: Self-synchronous vibration system is a mechanical dynamic system with features of synergistic motion. In the system, the coupling effect comes from the interaction between the rotary motions of two eccentric rotors, thus changing the motional characteristics and forms of the system. A differential equation was derived with an analytical method of nonlinear vibration for the coupling motion of two eccentric rotors to describe mathematically the coupling parameters of the system. Based on the phase space theory, the nonlinear characteristics of coupling motion were analyzed, as well as the influence of coupling intensity on the equilibrium state. The variation range of coupling parameters was also defined. Furthermore, the synchronization development course of two eccentric rotors was studied in depth, and the necessary coupling conditions to form a synchronization state are deducted. Finally, engineering applications of synchronous vibration system were discussed, including the design and selection of structural parameters.