圖書館的「線上公用目錄」（On-Line Public Access Catalog, OPAC）系統，是提供讀者查詢圖書館館藏資料的重要工具，也是早期資訊檢索技術主要的應用方向。本文即以輔仁大學圖書館為例，說明整合新一代資訊檢索技術於OPAC系統的實施現況。我們運用非營利機構可獲得的先進檢索引擎，輔以自行發展的關鍵詞擷取技術，完成具備重要性排序、近似字串、模糊搜尋、相關詞回饋、允許近似自然語言檢索字串的 OPAC 系統。初步的評估發現，這樣的系統對協助使用者簡化查詢條件、拓展檢索字彙、提昇檢索成效有相當的助益。

　　　　　The On-Line Public Access Catalog (OPAC) system is an important tool in helping users to retrieve information from a large volume of data stored in a library. However, recent advances in information retrieval technologies have not yet been applied to most OPAC systems. This paper introduces the development of a novel OPAC system which applies a free advanced search engine available from the Internet and an automatic keyword extraction function developed by the Department of Library and Information Science. The resultant features of the OPAC system include relevance ranking, fuzzy search, relevance feedback, and query by quasi-natural language. Results show that such a system greatly simplifies query formulations and automatically prompts more relevant search vocabulary to the users, thus improving the performance of an OPAC system to a higher degree.