We　will　study　the　effective　value　of　the　angle　which　affect　on　the　bolted　joint　surface　by　the　experimental　research　method.　It　gets　the　effective　angle　under　different　conditions　in　the　experiment　by　the　way　of　researching　the　joint　surface　stiffness　which　changing　during　the　joint　surface　area　changing　in　the　paper.　This　results　provide　valid　reference　for　the　mechanical　structure　design　which　with　the　bolted　joint　surface,　so　as　to　achieving　the　purpose　of　more　efficiency　during　the　mechanical　structure　design.　©　(2013)　Trans　Tech　Publications,　Switzerland.