The　bolted　joint　is　the　important　fastening　parts　of　structures.　Its　fatigue　and　self-loosing　will　affect　the　safety　of　the　system.　In　this　paper,　the　finite　element　contact　models　are　built　to　analyze　the　mechanical　property　of　bolted　joint　numerically.　The　stress,　strain　and　clamping　force　when　the　bolted　joint　is　subjected　to　preload,　axial　force　and　transverse　load　are　investigated.　The　results　show　that　the　bolt　is　the　most　dangerous　part　of　bolt-nut　connected　member.　The　clamping　force　of　bolted　joint　will　gradually　lose　with　the　increasing　loading　cycles　of　cyclic　transverse　load　which　generally　explains　the　stress　loosing　rule　of　bolted　joint.