This paper studies the vibration self-synchronization features of a type of planar single-mass nonlinear vibration system under the non-resonant condition. First, a vibrating system driven by two counter-rotating motors was taken as a research object. The nonlinear factor of the elastic component was considered. The dynamical model of the system was established using Lagrange's equation. The condition of the self-synchronization implementation of the system was obtained based on the Hamilton theory. The condition of steadily synchronous operation was obtained using the first order approximate theory stability criterion. Then, the computer simulation was performed using MATLAB/Simulink and applied the fourth order Runge-Kutta method. The theoretical calculation of the self-synchronization condition and the stability condition was obtained based on the simulation. Finally, the experiment of a single-mass vibration prototype was carried out. The simulation results show that the vibration system can achieve steady 0-phase synchronous motion. Comparison among the theoretical calculations, simulation results and experimental results prove the accuracy of the self-synchronization feature of the nonlinear vibration system.