2001年國科會開啟數位典藏國家型計畫，為使各機構及一般大眾能分享及整合 檢索各單位所建置的數位資源，聯合目錄的建置是當務之急。聯合目錄的建置模式可分為兩種：一種是集中式的聯合目錄，另一種為分散式查尋的虛擬聯合目錄，集中式聯合目錄的優點是檢索效能佳，但其缺點是建置成本昂貴。虛擬聯合目錄的優點是建置成本低廉，但是檢索效能差。為保留上述集中式聯合目錄及虛擬聯合目錄的優點，且避免其缺點，在數位時代，一個新的分散擷取metadata的協定──OAI (Open Anehives Initative) 就應運而生。本文主要在分析幾種不同的聯合目錄建立模式，並以數位典藏國家型計畫為例，說明選擇 OAI 做為國家數位典藏聯合目錄建置機制的原因，及此系統的架構、功能、實作時所遇到的問題。

On January 1, 2002 the National Science Council of Taiwan launched the National Digital Archives Program (NDAP). In order to share and conserve all valuable collections, retrieve the digital collections of the content holders via a union interface, and allow the general public to access the digital collections in Taiwan, the need to build a union catalog of National Digital Archives has been urgent. In this article, we define the functions and the system architecture of the OAI-based union catalog system and explain the problems we encounter in developing it.