The invention discloses a replica-based dynamic metadata cluster system which comprises a client-side module and a server module, wherein the client-side module runs at a client side; the server module runs on each metadata server node in a metadata server cluster; the client-side module is used for sending a metadata request to the corresponding metadata server node, and adjusting sending of a read request of the client side according to load information, so that read load is distributed on the metadata server nodes; the server module is used for maintaining MLTs (metadata lookup tables) buffered in all the metadata servers in the metadata server cluster, migrating metadata during addition of a new metadata server node into the cluster and during recovery period of metadata, and counting the load information on each metadata server. According to a method disclosed by the invention, load is balanced via replicas; and expandability of the cluster, and service performance and availability of the metadata cluster are improved via a replica-based dynamic metadata cluster scheme.