This article is a study of the transcript of Hsu T'ingMi-Shih-So Ching, which was first discovered in Dunhuang. By researching the rituals of the Nestorians, the history of scriptural interpretation and the religious system of Tang dynasty, the author concludes that the transcript was neither a direct translation from the original one nor a collection of translations, but a record of sermons by the Nestorian clergies. The manuscript had many erros, such as words missed, confusing titles, reversed sentences, inappropriate and inconsistent translations, etc. These errors were caused by, for example, a lack of understanding of the religious culture, some misunderstandings of the language, and errors of the live preaching. Some mistakes of the manuscript were difficult to identify, but we can explain them by analyzing the formation of the origin text.