We propose a multiple-tree overlay structure for re-source discovery in unstructured P2P systems. Peers that have similar interests or hold similar type of resources will be grouped into a tree-like cluster. We exploit the heterogeneity of peers in each cluster by connecting peers with more capacities closer to the root of the tree. The capacity of a peer can be defined in different ways(e.g. higher network bandwidth,larger disk space,more data items of a certain type etc.) according to different needs of users or applications. We propose a multiple-tree overlay structure for re-source discovery in unstructured P2P systems. Peers that have similar interests or hold similar types of resources will be grouped into a tree-like cluster. We exploit the heterogeneity of peers in each cluster by connecting peers with moreors closer to the root of the tree. The capacity of a peer can be defined in different ways (eg higher network bandwidth, larger disk space, more data items of a certain type etc.) according to different needs of users or applications.