Z39.50 is widely used for searching and retrieving information spread over a number of heterogeneous sources, but it is hard to construct the mapping relationships between Z39.50 and the data sources, since the semantics of the dynamic and autonomy data sources cannot be exactly derived so as to achieve an exact information retrieval operation. This paper proposes the extend hyper graph data model based on HDM, which can be abstracted into levels, taking two kinds of nodes and edges of EHDM as access points ofZ39.50. It can solve the problems of badly supporting of querying on structured data sources and query failures by constructing the DL layer between EHDM and Z39.50, in which the concepts and derived concepts are mapped onto Z39.50 wrappers. Thus, defining three layers structure as in dataspace systems can realize the data integration strategy named “integrate when needed”.