As "The Leader of Confucian Scholars", Dong Zhongshu demonstrated "popular support is Mandate of Heave" from the height of metaphysics. Every regime which win popular support must be a regime which adjusts itself to be accepted by the mandate of heaven. Every regime which lost popular support must also be a regime which negated and even abolished by mandate of heaven. Based on the analysis of a series of propositions and thought of "Popular Support Is Mandate of Heave", we find Dong Zhongshu tried to demonstrate the fundamental problem of political philosophy-What is the good of politics? Dong Zhongshu answered to the question and expressed his views on the good of politics-Beyond the realistic private interests, base the realistic political system, political decision, political ethics, system ethics and social political ideal goals on the Confucian kindheartedness and justice which functions as cultural attachment and moral spirit, take whether the regime love the people or not as a political principle, and hold whether the regime meet the kindheartedness and justice or not as the ultimate goal of social politics. Legislation for the world is the social mission which Dong Zhongshu diligently strive after.