This thesis hopes to propose a new hypothesis about the origin of Chinese heptasyllabic poetry. Although there are numerous academic discussions in the existing poetic narrative, few of them have noticed the possible effect of the Celestial Master Daoism. Based on the literary analysis and formal comparison, this thesis first finds that, during the time Cao Pi曹丕 created his “Yange xing,” the first literati heptasyllabic poem, “cypress beam genre” (boliang ti柏梁體) poetry – the earliest form of heptasyllabic poetry – was already a normal, fixed, and mature poetic form within the community of Celestial Master Daoism. Therefore, Celestial Master Daoism’s mastery of boliang ti poetry and their intensive and frequent composition highly likely motivated Cao Pi, the new Wei ruler who took over the populace of Celestial Master Daoism and had a close relationship with Zhang Lu’s張魯 family, to learn and introduce this poetic form into his own poetic creation. Then, this thesis also traces this poetic form back to suburban sacrifice songs in the Han dynasty. During the reign of Emperor Wu, the prototype of boliang ti poetry appeared in suburban sacrifice songs created to express worship to heavenly and earthly deities. Hence, when the Celestial Master Daoism became the inheritor of regional power (mainly in Sichuan, Chongqing, and Shaanxi of today’s China) of the Han empire and hoped to establish their own regime, they created their own ritual texts by modeling after Han suburban sacrifice songs. In so doing, they demonstrated their legitimacy and exclusivity by connecting the regime itself with Dao.