Abstract: Self-synchronization and synchronic-drive vibration have been successfully applied in many engineering fields. An in-phase self-synchronous vibrating system with vibrators deviating from its center of mass is put forward. Based on Lagrange principle, a dynamic model is derived to give its electromechanical-coupling model and, based on the mathematical model, a simulation model is developed. The simulation results showed visually the processes in which the vibratory machines implement fully the transition from asynchronous to synchronous state or from one type of synchronous state to other type, which the conventional mechanic models are unavailable to explain quantitatively. Thus, the characteristics of self-synchronous vibration of vibrating system with vibrators deviating from its center of mass are revealed to provide a theoretical basis for designing similar products.