A method for improving metadata service reliability and a relative system belongs to computer memory technical field, for fully utilizing node resource to improve the reliability of metadata service. The inventive method comprises normal operation, main metadata server accident, backup metadata server lift, sub metadata server accident and second backup metadata server lift. The inventive system comprises a client node, a memory node, a main metadata server and a sub metadata server, which respectively comprises an object metadata service module, a memory resource manage module, and a high available module, wherein the high available module comprises a metadata copy module, an accident shield module, a detect module and a select module, the select module can select the memory node with minimum load as the backup metadata server, and the accident shield server is switched to next metadata server, and selects the backup metadata server to form a master-salve backup chain service mode, to improve the reliability of metadata service.