Identifying　protein　interface　is　crucial　for　the　prediction　of　protein-protein　interactions　and　for　protein　functional　classification.　In　this　work,　the　protein　structure　is　modeled　as　an　undirected　graph　with　the　conservation　aminoacid　residues　the　vertices　and　all　atom　contacts　between　them　the　edges.　We　find　that　the　conservation　residue　networks　are　characterized　by　intermediate　values　of　clustering　coefficient　and　characteristic　path　length,　which　are　the　typical　property　of　small-world　networks.　The　residues　on　the　protein　interfaces　typically　have　higher　degree　and　lower　clustering　coefficient　values　than　that　of　the　surface　residues.　Additionally,　it　is　detected　that　the　spatial　clustering　of　the　conservation　residues　is　a　general　phenomenon,　consistent　with　the　cooperative　nature　of　residues　in　determining　the　structure　and　function.　These　results　indicate　that　the　conservation　residue　network　propensities　can　give　us　some　new　parameters　in　protein-protein　interface　prediction.　©　2007　IEEE.