The feudalism of Western Zhou was an important ideal in political system of Medieval China. The law of feudal lords was created by Western Jin Dynasty, but it was abandoned by Dynasties except North Zhou Dynasty. This paper focuses on the analysis of Law of feudal lords, which bornd and disappeared in Medieval China. This paper also discusses the legislative background of Law of feudal lords. Those feudal lords had Lofty status, so they shouldn't became the object to be punished. The disposal of feudal lords was political issues, rather than legal issues. The birth of the law of feudal lords, not only showed that Western Jin government tried to ”rebuilding” the feudal system of Western Zhou, but also constrainted the power of the emperor. The law of feudal lords was only for embellishment in medieval China.