Human society can construct a nicer government by way of political design and constitutional design is a basic approach to realize human good and construct a nicer modern society.Human beings have subjectivity and politics has the characteristics of goodness,which makes constitutional design possible.Constitutional design would follow some theoretical hypotheses,e.g.hypothesis of gloom consciousness of humanity and hypothesis of essential evil of power. Human society can construct a nicer government by way of political design and constitutional design is a basic approach to doing human good and construct a nicer modern society. Human beings have subjectivity and politics has the characteristics of goodness, which makes constitutional design possible .Constitutional design would follow some theoretical hypotheses, eghypothesis of gloom consciousness of humanity and hypothesis of essential evil of power.