this paper introduces the current practice of building a network of institutional repositories (ir_s) at chinese academy of sciences (cas), which is named cas ir grid. national science library (nsl) of cas plays a leading role in the construction, promotion and implementation of cas ir grid. it aims to promote each institute of cas to build ir of its own, and finally form the ir network of cas institutes. nsl's experience is introduced in coordinating and supporting institutes' building of their respective irs and promoting ir services by adopting collaborative and progressive development strategies. achievements made during the development of cas ir grid are described and challenges for its future development are discussed. the authors aim to provide best practices for developing a network of institutional repositories in research institute settings, which can serve as a practical reference to other institutions engaged in the similar task.