Abstract：BlueOcean system is a large distributed storage system based on object-oriented Storage technology. This paper describes the design and implementation of a highly concurrent client in BlueOcean system. This highly concurrent client is developed based upon the FUSE framework, which guarantees the generality and reduces the difficulty on developing and maintenance. The client implements most POSIX interfaces, and it can support most existing application. In addition, the client is implemented using the event-driven model. When accessed by multi applications simultaneously, the client improves the performance significantly comparing with the traditional synchronization client. The results of the experiments show that, when the BlueOcean storage system is outputted by the highly concurrent client, the data read/write performance, metadata operations performance and transactions performance of the overall system has a significant performance improvement.