Because　of　the　friction　and　damping　effect　between　the　interfaces,　when　the　bolted　structure　bears　the　axial　load,　there　will　be　no　interface　dislocation　and　only　axial　reciprocating　tension　and　pressure,　so　it　is　difficult　to　have　fretting　fatigue　and　wear.　Only　under　the　tangential　load,　the　interface　will　be　staggered　and　the　peaks　and　valleys　between　the　micro-convex　bodies　will　be　alternately　rubbed.　After　repeated　cycles,　the　interface　will　generate　sliding　and　adhesion　areas　of　micro-fatigue　and　wear.　Therefore,　this　paper　conducts　an　in-depth　study　on　the　influence　of　bolt　relaxation　on　surface　fretting　fatigue　and　wear.　The　relationship　between　tightening　torque　and　clamping　force,　design　and　implementation　of　tangential　relaxation　experiment　and　acquisition　and　analysis　of　3d　surface　topography　are　studied.　©　Published　under　licence　by　IOP　Publishing　Ltd.