Abstract: The term "ziyou" (freedom) appeared as early as the Eastern Han Dynasty in ZHENG Xuan's Commentary on the Book of Rites. It was repeatedly used in the historical records such as the Book of the Eastern Han Dynasty. In these books, it mainly means a negative value referring to an individual's willful behavior that disobeys social system or order. However, it is quite positive in Tang poetry in the following five aspects:1. Resisting the constraint or the lack of liberty in politics or in official circles; 2. Complaining the lack of freedom in personal life and feelings; 3. The free will related to self-independence; 4. The free will related to the ultimate religious freedom; 5. The feeling of pleasure when one enjoys freedom. The former three express the longing for freedom when it is absent, while the latter two positively express and confirm the value of "ziyou". YAN Fu was correct when he claimed that "ziyou" was a value about which Chinese sages were apprehensive, not to mention basing their teachings on it. However, in Tang poetry, we can see that "ziyou" has become a positive value that some poets pursued. It is our duty to study traditional culture so as to elaborate and highlight the cultural heritage that is conducive to promoting contemporary values.

Key words: Tang poetry, “ziyou”, history of philosophy, “in a strict sense” and “in a broad sense”