Abstract: From the enfeoffment during the years of Taishi to the reform in the 3^rd year of Xianning and then to the 3^rd year of Taikang when the Prince You of Qi was sent to his own fiefdom by force, it is evident that Emperor Wu was intended and determined to build a feudal system of five levels similar to that of the Zhou Dynasty by sending royal members to different fiefdoms. In the end of the 10^th year of Taikang, Emperor Wu established "super kingdoms" over the "great kingdoms" to enfeoff the princes. His grown-up princes were enfeoffed to the states of Yong, Jing and Yang so as to form the pattern of protecting the capital Luoyang, which can be regarded as the further development of the feudal system of five levels. The vast territories and large populations of the feudal states of princes, as well as princes being sent to important feudal states—such phenomena had never seen since the early years of the Han Dynasty. On the one hand, Emperor Wu's feudal system of five levels was strongly influenced by the Confucian ideal; on the other hand, it was also a response to the realistic demand of rising the imperial power and keeping the throne to Emperor Wu's son Emperor Hui and his grandson. This system, as the profound background of political disputes at that time, is the key to understand the political system of Emperor Wu's court. Moreover, it also significant to study the rise and fall of the imperial relative YANG Jun, which was closely related to the reform during the years of Xianning and the enfeoffment during the years of Taikang.

Key words: the enfeoffment in the 10^th year of Taikang, Emperor WU in the Western Jin Dynasty, YANG Jun