The vibration angle greatly affects the performance of the vibrating machine in screening efficiency and conveying speed. In order to achieve the dynamic adjustment of the vibration angle, the influence of the motors′ supply frequencies on the vibration angle is studied with a dual-machine vibrating system. First, a dynamic model is established using the Lagrange method. The theoretical analysis demonstrates that two vibrating motors achieve stable synchronization at different supply frequencies, but the vibration angle changes. Then, the simulation model is established by the numerical method. The elliptical trajectory of the system is obtained and the law of the vibration angle with the supply frequency is analyzed. Finally, the experiment of the dual-driven elliptical vibrating machine is carried out to verify simulation results. The simulation and experimental results show that the stable synchronous state of the vibrating system changes and the vibration angle is adjusted while the frequencies of the two vibrating motors are changed and under the condition of self-synchronization.