In ancient China, folk songsdirectly reflected the real life and true feeling of the commonplace. However, they usually interested the ruling class too. Under some special situation, they could even result in the interactionbetween government and the common people. It was a typical representation of theinteraction during the period of the Wei-Jin and South and North Dynasties that the ruling class changed their policies in accordance with the will of the common people expressed through folk songs. This representation can be loosely categorizedinto the following four aspects. First, the supreme rulers could appoint or remove officials under the influence of folk songs. Secondly, they could change their military and political measures enlightened by folk songs. Thirdly, they could realize the superseding of royal regimes under the cover of folk songs. Fourthly, they could replace the old reign title by a new one and practice the ceremony of pray to meet the demand of folk songs. The four measuresall contained some democratic elements. Therefore, they had some active significancefor the social stability in those days.