In　order　to　broadcast　stream　media　data,　a　solution　method　of　application　layer　multicast　is　designed.　The　solution　can　construct　and　maintain　a　multicast　tree　to　support　the　communication　among　different　kinds　of　LAN　with　NAT-traversal　technology.　An　advanced　destination-driven　shortest　path　algorithm,　which　utilized　network　latency　to　build　the　low-cost　shortest　path　tree,　is　proposed　as　the　fundamental　conception　of　the　solution　method.　The　algorithm　can　minimize　the　latency　from　source　to　destination　and　reduce　the　bandwidth　consumption.　The　maintenance　strategy　of　the　multicast　tree　can　rebuild　the　multicast　topology　efficiently　and　strengthen　the　robust　of　the　multicast　tree.