Abstract. With the development of the multicast technology, the realtime strategy among the group applications using the multicast routing is getting more important. An essential factor of these real-time applications is to optimize the Delay- and delay Variation-Bounded Multicast Tree (DVBMT) problem. In this paper, we propose Estimation of Selecting Core (ESC) algorithm for DVBMT solution. Furthermore, it is expected that ESC algorithm results in the better any other DVBMT solutions.