檢視河上公《老子注》之現存版本，發現歷代原書所迴避之帝諱，包括西漢高帝劉邦、惠帝劉盈、文帝劉恒、景帝劉啟、昭帝劉弗、東漢桓帝劉志、隋文帝之祖、宋太祖趙匡胤、宋仁宗趙禎以及宋孝宗趙昚，其中以對惠帝劉盈之避諱與回改現象最為關鍵。本文運用避諱學、校勘學、史學等知識，考訂出河上公《老子注》之成書年限在西漢元帝永光五年至竟寧元年之間（39-33B.C.）。

An investigation of extant editions of He Shanggong’s 河上公 Annotation of the Laozi 老子reveals the use of the taboo against mentioning the personal names of the following emperors: Han Gaozu 漢高祖, Han Huidi 漢惠帝, Han Wendi 漢文帝, Han Jingdi 漢景帝, Han Zhaodi 漢昭帝, Han Huandi 漢桓帝, Sui Wendi’s 隋文帝 grandfather, Song Taizu 宋太祖, Song Renzong 宋仁宗 and Song Xiaozong 宋孝宗. The phenomena of taboo characters and diction modification are particularly obvious with regards to Han Huidi. This essay employs the methods of taboo character analysis, textual criticism and historiography to date He Shanggong’s Annotation of the Laozi to the reign of Han Yuandi (39-33 B.C.), concluding that it was completed between the fifth year of the Yongguang 永光 reign period and the first year of the Jingning 竟寧 reign period.