The network resources are limited in opportunistic networks. For improving the effectiveness of nodes’ storage resources, this paper proposes a proper method to estimate node’s activity degree. Based on the node’s activity degree, we estimate the messages’ importance degree, and then design a message importance degree aware adaptive queue management mechanism (MAQM) by the importance of message. This mechanism estimate node’s activity degree by its meeting times with other nodes, and estimate messages’ importance degree by node’s activity degree .Simulation results show that the method to evaluate node’s activity degree is accurate.Deviation is less than 5%. Tompared with other cache management mechanisms, MAQM can improve message delivery rate effectively, while reducing latency and overhead ratio.