The present invention provides an Ethernet ring system and the master node and the initialization method thereof, comprising the following steps: Step 1, a master node of an Ethernet ring protection domain is generated from nodes on a ring; Step 2, the master node detects the link state of a primary port and a secondary port wherein if the master node detects that no fault occurs in the link of the primary port and the secondary port, it records the state of the ring network as the initializing state and blocks the secondary port; Step 3, the master node sends a link health check message to the ring network periodically; Step 4, it is judged whether the master node receives the link health check message in a prescribed time period wherein if receiving the message, it records the state of the ring network as intact, continues blocking the secondary port and sends a ring network restoration notification message to the ring network, informing other nodes that the state of the ring network is intact, so as to realize the initialization of the master node.