The invention discloses a metadata service optimizing method and system of a network file system. The method comprises the following steps: organizing all metadata servers in the network file system to form a two-level tree structure in advance, and creating corresponding root directory cache file; when a Lookup operation instruction initiated by a client for the target metadata in any metadata server is received, determining the metadata server corresponding to the target metadata by use of the root directory cache file; and obtaining a path analysis request sent by the client to the metadata server corresponding to the target metadata, and controlling the metadata server to respond to the path analysis request. According to the invention, the metadata server can be quickly positioned, thus the time of path finding and whole process analysis is remarkably reduced, and the data access performance of the network file system is further improved.