Legal system and moral system are the two core means for the rulers of past dynasties to rule steadily. Generally speaking, the German system pays attention to ruling through moral persuasion. The legal system focuses on political achievements. However, these two thoughts were mixed with each other in the Han Dynasty, forming a complementary ruling technique. Xuan Di used to use more criminal officials. When the Prince (Yuan Di) suggested that he use more Confucian scholars, his answer was: "The Han family has its own system, which is based on the hegemony of Taoism. How can it be pure moral education and weekly politics? " It shows that the rulers of the Han dynasty have consciously combined Confucianism and law to rule. Putting a layer of benevolence on feudal rulers, internal law provided a strong backing for the autocratic rule of rulers. Confucianism believes that there are ethical constraints of "monarch, monarch, minister, father, son and son", but this ethical constraint is not mandatory by law, so the "three cardinal guides" of "monarch as minister, father as child and husband as wife" have emerged. On the ethical basis, although there are obvious hierarchical constraints, there will also be "the monarch wants to die, and the minister has to die; The feudal law that the father wants his son to die and the son has to die. The legalization of ethics stipulates all feudal ethics in the form of law. Violation of moral norms is no longer a moral judgment, but a legal sanction. In a sense, the structural form of feudal patriarchal society is the inevitable product of Confucian rule and internal laws. Feudal law was clothed with a kind coat of "Confucianism outside and sage inside", which made all laws find ethical support. When we open the law books of past dynasties, we can find that they all wore a hat of benevolence, morality and ethics at the beginning. This result, on the one hand, can leave a way for the rulers to cover up and connive at crimes, and also provide a convenient door for the law to extend to every social cell. As long as the rulers are unwilling to punish the people, emperors or local officials can easily "forgive" them and give them a chance to turn over a new leaf. In this way, they will not be responsible for "bending the law", but will show the generosity and compassion of the rulers. When criminals appear with the family as the social cell, the ruler can enlarge the crime of a family member to the crime of the whole family: the family failed to implement the moral standards well, resulting in such scum! So the torture of destroying nine families and even seats can be used openly. It is on this basis that "full door copying" can be implemented. At the same time, this combination of Confucianism and law can also be extended to every cell in the feudal patriarchal society, especially in the later period of feudal centralized rule, the state "delegated" the legal system to the clan, and the clan leader had the right to punish the clan by legal means. At this time, the law protects not the interests of the clan, but the stability of the clan system: as long as the clan leader thinks it is wrong, he can punish the clan in the ancestral hall. This is why private courts are not regarded as crimes in feudal society.