We　propose　a　scheme　of　privacy　preservation-using　friendly　peers　as　proxies　during　date　requesting　and　sending.　This　proposed　scheme　removes　the　immediate　association　between　the　identity　of　the　participator　and　the　accessed　data.　Meanwhile,　it　can　prevent　some　malicious　attrack　and　strengthen　system　security.　In　order　to　verify　the　effectiveness　of　our　proposed　scheme,　experiments　have　been　carried　out.