For supporting Peer to Peer (P2P) based live media streaming, a P2P overlay network should be able to accommodate robustness, peer heterogeneity, and scalability. In this paper, we have proposed a Hybrid P2P Overlay (HyPO) approach for live media streaming. In the proposed scheme, the overlay network consists of mesh and tree overlay. The mesh overlay is organized by peers that have the similar bandwidth ranges in geographical place. The tree overlay is formed by stable peers, and is constructed over the mesh overlay. We have pursued the robustness of transmission structure by promoting peers that are considered stable in the mesh overlay as members of tree overlay. Depending on the tree optimization mechanism, the peers which have a large bandwidth will be near to the media source node in the tree overlay, and evenly distributed in the tree with branches of a similar depth. As a result, the tree optimization reduces the average depth of the tree, which enhances the scalability. We evaluate HyPO through simulation. The results demonstrate the efficiency and scalability of our HyPO.