The invention relates to a method suppressing resonance of a direct current power supply system. The method is characterized in that a series reactor is arranged between a direct current charger and a battery group; and a resonance point is controlled in a frequency range which does not produce alternating current component. According to the invention, with a small investment, the reliability and the stability of the operation of the direct current power supply system are improved; the problem of the service life of a car battery and other civilian products is well solved; and the method and the system play a decisive role in the promotion of an electric car.