<p>In the opportunity network, effective buffer management methods are important means to improve network performance when buffer overflow. Therefore, this article proposes a message grouping based opportunistic network buffer management method. This method first determines the relationship between the buffer space required to receive all messages in the message set and the size of the idle buffer of the node. If the idle buffer of the node is not less than the buffer space occupied by the message set to be received, all messages to be received are received. Otherwise, the number of messages in the message set to be received is further determined, and which messages in the node buffer to discard are selected based on the number of messages in the message set to be received, thereby alleviating the problem of buffer overflow. The simulation results show that the algorithm proposed in this paper outperforms Drop Oldest algorithm and Drop Largest algorithm in terms of delivery ratio, delay and network overhead.</p>