This study examines the Venerable Dao An's opposition to geyi (格義). Geyi was originally a tool employed to comprehend Buddhism in terms of Chinese traditional thought. As a youth, Dao An studied geyi diligently, but later in life he rejected it openly. Why? Did Dao An see the limit of geyi and find another way to Buddhism when he decided to put it aside? Firstly, this study sets out to explore the background on which Dao An came into contact with geyi. It reveals that Dao An derived his idea of geyi from Zhu Fa-Ya. Some contemporary scholars hold that geyi brought about the conflation of Lao-Zhuang Daoism with the Pâramita Sutra. So, then what classical works did Dao An and Zhu Fa-Ya master under the influence of Fotudeng? What were the most popular works in Northern China? Was it truly the Pâramita Sutra? Did Dao An intend to solve the problems in the Pâramita Sutra when he decided to study geyi in his early days? Secondly, Was Dao An's rejection of geyi of his own realization or was he influenced by others? What were the internal and external influences that led to this rejection? What theories influenced him sufficiently to lead him to give up the conventional approach to sutra interpretation? What was his new approach to sutra interpretation? Can we find any evidence in extant documents? These are the main concerns of this study.