The invention provides a method for realizing an opportunistic routing mechanism applicable to a multi-radio-frequency multi-channel Ad hoc network. The method comprises the following steps of: establishing candidate forwarding node sets with priorities on control channels through routing requests and routing reply information, wherein if a node is closer to a host node, the priority of the node is higher; sharing channel state information by periodically broadcasting HELLO packets; constructing neighbor lists stored with channel interference values; through calculating an average channel interference value of potential forwarding node sets, choosing forwarding channels according to interference situation of receiving ends so as to reduce channel interference; and preventing repeated forwarding of data packets through priority comparison and cross-layer acknowledge character (ACK) coordination so as to increase packet delivery ratio. By the multi-radio-frequency multi-channel opportunistic routing, a plurality of orthogonal channels can be fully used; network throughput is increased exponentially; and through an opportunity forwarding mechanism, forwarding nodes which are closer to the host node can be fully used for forwarding in a scenery with poor channel quality, so that the delivery ratio is high, and end-to-end time delay is small.