This paper proposes a novel approach to integrate heterogeneous data in P2P networks. The approach includes a tool for building P2P semantic link networks, mechanisms for peer schema mapping, criteria for peer similarity degree measurement, and algorithms for heterogeneous data integration. The approach has three advantages: First, it uses semantic links to describe semantic relationships between peers' data schemas. Second, it deals with the semantic heterogeneity, the structural heterogeneity and the data value inconsistency. Finally, it considers the semantic similarity and structural similarity to forward queries to relevant peers. Categories & Subject DescriptorsH.3.3 [Information Storage and Retrieval]: Information Search and Retrieval ? query formulation, search process, selection process. General TermsAlgorithms, Management, Measurement. Keywords Data Integration, P2P Computing, Semantic Link, Semantic Web.