Bamboo is one structured P2P overlay, that likes others (e.g. Chord, Kademlia, Pastry), organizes peers into a flat overlay network and offers distributed hash table (DHT) functionality. It is very promising for its efficient routing performance. However, one disadvantage impeding the DHT algorithm popularity is the routing information maintenance overhead; it generates considerable network traffic and increases P2P system complexity, especially in a highly dynamic environment. Besides, in this structure, all nodes have identical capabilities and responsibilities and all communication is symmetric. In this paper, taking the node heterogeneity into consideration we propose an improved Bamboo based on hierarchical network model to resolve this problem. Furthermore, the routing tables, lookup service and the procedure of node operations will be carefully discussed.