Aimed to the requirement of dynamic mass storage of "digital city", and based on analysis of the load characteristics of its storage, a separation of read and write distributed metadata management method is proposed. This method integrates the directory sub-tree partitioning with Hash algorithm together. On the one hand, the full development of the di-rectory storage locality. On the other hand the efficient protection of the system load balan-cing. At the same time, in order to ensure writ performance of system, release control algo-rithm based on service demand is taken between the separation of the two types of metadata server. The experimental results of prototype system show that the proposed method has ob-vious advantages in improving the system performance, equalizing metadata distribution.