Most of the existing security Mobicast routing protocols are not suitable for the monitoring applications with higher quality of service (QoS) requirement.A QoS dynamic clustering secure multicast scheme (QoS-DCSMS)based on Mobicast and multi-level μTESLA protocol for large-scale tracking sensornets is presented in this paper.The multicast clusters are dynamically formed according to the real-time status of nodes,and the cluster-head node is responsible for status review and certificating management of cluster nodes to ensure the most optimized QoS and security of multicast in this scheme.Another contribution of this paper is the optimal QoS security authentication algorithm,which analyzes the relationship between the QoS and the level Mofmulti-level μTESLA.Based on the analysis and simulation results,it shows that the influence to the network survival cycle (NSC) and real-time communication caused by energy consumption and latency in authentication is acceptable when the optimal QoS security authentication algorithm is satisfied.