Abstract: Wugong Nobility was newly founded in the period of Emperor Wu of Han Dynasty. Many scholars in the past believed that this had been to solve the problems of difficulties in finance and award of military service. Accordingly, "Wugong nobility" was taken as a temporary measure to encourage those with military exploit. But from the history of early period of Western Han Dynasty, the setting of "Wugong Nobility" was the extension of action to perishing Qin's traces by Emperor Wen. Its purpose was to replace the tweenty nobility ranks of military exploit inherited from Qin in an attempt to weaken the influence of the "Qin system" on the "Han one". And as a result, it would show the orthodox regime of Han, promote the political and military achievements of Han Dynasty, and then realize the unification between system and ideology.