[Purpose/significance] The Open Access movement has brought new opportunities for the development and utilization of ancient books. Open Access of digital resources of ancient books will become the future trend of development in the collection of ancient books. [Method/process] This article introduced the background of Open Access of Ancient Books (OAAB), summarized the features and research status both at home and abroad, and introduced the present situation of international cooperation. From the perspective of coverage, standard, degree and pattern of openness, we compared the status quo of OAAB across the globe. [Result/conclusion] Domestic libraries are quickly adapted to the new pattern of the global collaboration. Though still with a lower degree of Open Access, the continuous advancement in the digitization of ancient books and the ever-deepening concept of OAAB will undoubtedly lead to great progress in research and practice of OAAB in China.