線上檢索萌芽於1960年代，歷經1970年線上檢索系統的開發，1980年代光碟資料庫的蓬勃發展，以及1990年代科技的利用和網際網路的普遍，已成為圖書館不可或缺的服務項目之一。近年來資訊與通訊科技的持績發展及各種電子型式的資訊資源資源不斷增加，由於科技的發展帶來更多的方便同時也帶來更大的挑戰，導致線上檢索服務也變得越來越複雜。本文將從線上檢索的發展歷史，探討它在參考服務的應用與優缺點，和規劃線上檢索服務相關的一些必備條件與重要因素，期圖書館在線上檢索方面，提供更完善更便捷的服務。

　　　　　The techniques of the online searching industry could be traced back to the 1960's. With the development of the online searching systems in the 1970's, a great boom in CD-ROM databases in the 1980's, and the application of technology and wide access to the INTERNET in the 1990's, online searching has been one of the indispensable services offered by the libraries. Technology in information and in telecommunication has been constantly expanding over recent years. There are more electronic information resources available online. Due to more conveniences as well as challenges advancing with the development of technology, online searching service turn out to be more complicated than ever before. In terms of the developmental history of the online searching industry, this paper will shed light on reference services in application, the advantages and disadvantages, and the major factors and essential conditions relevant to the planning for online searching service. We are in an attempt to provide the readers with preferable and convenient services in regard to the online searching.