Big　data　service　is　a　promising　technology　in　Internet.　Quality　of　service　of　big　data　services　is　a　very　important　indicator.　A　service　delivery　network　was　presented　in　this　paper　to　reduce　service　delays.　The　web　services　were　distribution　to　the　edge　of　the　network　to　making　it　closer　to　users,　so　the　network　delay　is　small.　A　services　distribution　method　with　QoS　guarantee　was　presented　in　this　paper.　Friendly　degrees　were　measured　in　this　method　between　the　servers.　According　to　the　friendly　degree　determine　the　coverage　areas　of　a　copy.　It　takes　up　less　resource　under　the　premise　of　QoS　guaranteeing.