Abstract: Data transmission in a distributed virtual environment（DVE） is required to be multi-source feasible,real-time,and highly safe.Based on the analysis of IP multicast and application layer multicast,we propose a hybrid application layer protocol（HALM） for the data transmission in the large scaled internet based DVE.HALM combines the grouping and layering mechanisms to achieve a stable and fast transmission of the simulation data in wide area network（WAN）,leading to high efficiency and performance of IP multicast,as well as plausible scalability of application layer multicast.We design a set of unique routing rules based on the determined structure of groups and layers,so as to satisfy the characteristic of multi-data source in DVE and the requirement of real-time transmission.Experimental results demonstrate the effectiveness of our approach.