It does not matter good or evil that human nature covers animal attributes and social attributes. The former covers two kinds of natural attributes which are sexual impulses and survival desire, and the latter includes cohesive combination mode and group life style. Family law legislation is not directly based on human nature but there should be the intervention of marriage and family ethics which is the result of moral evaluation of animal attributes and social attributes. Marriage ethics should regulate sexual impulses and cohesive combination mode in the ways of sexual taboos and chastity idea respectively. Family ethics should regulate survival desire and group life style in the way of the principle of non-injury, "cohabitation" concept and equal ethical spirit of property rights. Family law legislation should absorb marriage and family ethics to "do something but not everything". The humanity hypothesis of good and evil is the key reason affecting the value orientation of China and western family law. China's family law legislation should be based on individualism taking into account of the family-based holism.