《三家詩其文疏證》與《三家詩遠說》，是馮登府關於三家《詩》的主要作品，二書雖非純為輯佚而作，但輯佚三家《詩》卻同為首要步驟，故本文以此作為輯佚學的觀察對象。登府在二書結構上，由先分三家，其後改為以三百篇為次，不再強分所輯之說，此種變換，如實反應了從王應麟《詩攷》至范家相《三家詩拾遺》的演進軌跡；在輯佚方法上，由原先最可靠的直引法，發展出師承法及推臆法，使輯佚內容較原先豐碩；而其輯佚時的學術立場，從《疏證》時對《毛詩》與三家的不論高下，到《遺說》時三家勝《毛詩》多矣的說法，相較於范家相堅持《毛詩》為上的態度，不會為一鮮明對比。此外，登府深受阮元賞識與魏源影響，且與道光中葉的學術氣氛密切關連，其二書所呈現的種種現象，頗能為交織其間的重要因素提供許多訊息，實為三家《詩》輯佚史上不可或缺的重要著作。

Sanjiashi yiwen shuzheng and Sanjiashi yishuo were Feng Dengfu's major works about the Three Schools. Collecting and compiling lost texts of the Three Schools was the foundation of composing these books, though they were not written merely for that purpose. This paper focuses on Feng's endeavors at collecting and compiling lost texts (jiyixue). The two books were first organized around the Three Schools but were then reorganized according to the order of the three hundred poems. By no longer mechanically separating those collected writings into Three Schools, the books' structure reflected the evolution from Wang Yinglin's Shi Kao to Fan Jiaxiang's Sanjiashi shiyi. Feng expanded the methods of collecting and compiling lost writings, from directly citing the quotation to considerations of teacher-succession as well as inference and deduction. These methods increased the amount of collected materials. In Shuzheng, Feng Dengfu did not rank the value of the Mao tradition and the Three Schools, but in Yishuo, he was of the opinion that the Three Schools were far superior to the Mao tradition. His opinion was an obvious contrast to that of Fan Jiaxiang, who insisted on the Mao tradition's superiority. Moreover, Feng was highly appreciated by Ruan Yuan and greatly influenced by Wei Yuan; he was also deeply involved in the academic scene in the middle of the Daoguang period. His two books thus offer a significant testimony to the various aspects of the intellectual trends of the day. They are truly important works in the collection and compilation tradition of the Three Schools.