Constant advancing with the time constitutes the vitality of thought. In the Han Dynasty, the policy of advocating Confucianism only while rejecting all other doctrines was performed. This was due to the transformation from cultural Confucianism to political Confucianism in pre-Qin. This transformation advanced pre-Qin Confucianism to cultural Confucianism of mankind beyond particular times on the one hand, and also political Confucianism closely related to the life world. This transformation made later development of Confucianism possible. In addition, we can also learn much from this historical transformation for creative transformation and innovative development of Chinese traditional culture in the "new era".