The paper presents energy-efficiency opportunistic multicast routing protocol (EOMR) for the multicast energy consumption minimization problem in wireless sensor networks. The protocol divides the network into single grids, so each node determines their own coordinates according to the grid, which they locate in a certain period of time. The nodes only need to know the topology of their own grid, instead of the topology of the entire network. Nodes in the same grid determine the priority in light of the upstream and downstream links metrics, and use the opportunistic routing to send messages to the next hop. The destinations calculate the optimal path in accordance with the hops and links cost, and transmission acknowledgement to source along the optimal path selected. If all nodes in the current grid transmission messages failure, the neighbor grids are in charge of retransmission. The results of simulation show that, compared with traditional multicast routing, EOMR is effective in reducing the consumption of links cost, so that it improves the link reliability and reduces the delay.