晚清名士龔自珍，除了素為人知的詩人、思想家、經世學者等身分，他還是個虔誠的佛弟子。讀書遍三藏，本身長年作著修行功課，是個真正的佛教徒。他用實事求是的治學態度探討佛法，對佛典進行考據工作，在他心中這不是叛逆，而是釐正經典，為報佛恩。真誠信仰與切實的學問態度於他內在並不矛盾衝突，其中大膽釐正譯者之誤的佛典研究，在歷代佛教徒中，都是罕見的。本文旨在探討龔定庵學佛因緣與學佛歷程，並探討他的佛教信仰與佛學思想和他的經世理念之間的關係。從安頓心靈、撫平世道憂患，到恢弘大乘佛教信仰為經世濟世之動力，龔定庵的學佛，有著一個熱切憂世的知識份子，一個敏感多情的騷人，自我生命價值求索的精彩過程。

龔自珍 is a famous scholar in the late Chin dynasty. In addition to being a poet, philosopher, and learned man, he is also a pious Buddhist. He perused many the Buddhist Scriptures and practiced Buddhist all his life. He can be called a true Buddhist. He used practical attitude to discuss Buddhist doctrine and to delve into Buddhist Scriptures. What he did is not to disobey Buddhist Scriptures but to correct them in order to repay Buddha. His pious belief and practical attitude did not confront each other inside him. His research of correcting mistakes among translators of Buddhist Scriptures was rare among Buddhists in the past dynasties. This research paper focuses on the reason of 龔定庵's start to learn and keep Buddhist doctrine and the process of it. This paper also discusses the relation of his Buddhist’s belief, thought and his practical attitude. As a sentimental poet, 龔定庵 became a Buddhist to pacify the soul, make world a better place, develop Buddhist doctrine to teach the world. 龔定庵's being a buddhist is a process of a intellectual who eagerly cared the world and of searching for his own life value.