The paper focuses on the difficulties of building the Institutional Repository for Traditional Mongolian literature with DSpace and points out a technical route to solve the problem，including Mongolian digital data acquisition, storage, retrieval and display. Through analyzing the Mongolian characteristics in morphology and syntax, we improve on Lucene to implement the Mongolian search, including managing Term with  B tree，simplifying the calculation of Term weight，and determining the Mongolian stop list.