Abstract: The five-etiquette system established in Western Jin Dynasty was the one which adapted to the unified dynasty. The specific name about these five etiquette may have some relationship with the five elements of Yin and Yang. The concept of five-etiquette system formed during the late warring states period at latest. The first emperor of Qin established a unified feudal dynasty, who had outstanding contribution on establishing etiquette system. The system of etiquette of later generations followed the line created by the Qin Dynasty and developed forward. Confucianism was revived in the early Han Dynasty and the study about etiquette had experienced four obvious turns. The one is that the Emperor Wu of the Han Dynasty abolished the coercive order which forbade private collections about books, he set the policy to venerated Confucianism and scriptures written before the first emperor of Qin burned books and Confucian classics had appeared. All these made traditional study of etiquette which attached more importance to the moral turned to both morality and politics. Second, during the period of new regime by Wang Mang, Liu Xin made use of those more ancient texts to help Wang Mang’s usurpation of the Han Dynasty. Through which, the scriptures written before Qin had been established as orthodox learning. Then, the new etiquette system based on the ' national level” began to formulate comprehensively. The third, Zheng Xuan combined the theory of the studies based on the texts before Qin Dynasty and after which as a whole, which established a new etiquette situation placed more value on politics. The forth, Wang Su criticized Zheng Xuan and he founded another academic faction, which promoted the further development of the study of etiquette. The formation of five-etiquette system needed three prerequisites, which were imperial will, the foundation of the development of academic and the political situation at home and abroad, anyone of the three was indispensable. Emperor Wu of the Jin Dynasty put an end to the division, created a unified dynasty after a long time of war and division, he himself had the will to create a new system of etiquette, at the same time, the theory by Zheng Xuan and Wang Su had tended to be mature. Therefore, the five-etiquette system adapted to the unified feudal dynasty broke through the soil and finally formed.