<p>In order to achieve better network performance for opportunistic network, this paper proposes an opportunistic network routing algorithm based on adaptive message replica number adjustment (AMRNA). The algorithm first sets the update cycle of globally active nodes and determines the globally active nodes in the network based on their network properties. Secondly, after clustering the network, the algorithm will select cluster head nodes for each cluster. When a node has a message that needs to be forwarded, relay nodes will be selected based on whether there are cluster head nodes or globally active nodes among the optional nodes. Finally, in order to reduce the number of replicas of messages in the network, the initial number of replicas of newly generated messages will be set, and the number of message replicas during different global active node update cycles will be adjusted according to the performance of the network. The simulation results show that compared with the epidemic routing algorithm and the spray and wait routing algorithm, the algorithm proposed in this paper can not only improve the delivery ratio but also reduce delay and network overhead.</p>