Bolted　joints　are　widely　used　for　the　mechanical　assembly　of　engineering　structures　and　friction　coefficient　of　the　contact　surface　of　a　bolted　connection　is　the　main　factor　that　influences　its　structural　performance.　This　article　presents　a　mathematical　model　based　on　the　Florida　contact　model　to　obtain　the　friction　coefficient　for　the　contact　surface　of　a　bolted　joint.　The　pressure　distribution　function　of　the　bolted　joint　is　introduced　into　the　mathematical　model　and　elastic,　elastic-　plastic,　and　full　plastic　deformation　of　asperities　at　the　microscale　is　also　considered.　By　varying　the　peak　height　of　asperities,　an　improved　exponential　distribution　function　was　constructed.　In　addition,　the　proposed　model　was　verified　by　comparing　simulation　results　to　experimental　values　obtained　using　a　CETR　UMT-5　high-precision　ball-on-disk　friction　and　wear　tester.　Then　the　theoretical　friction　coefficient　was　used　in　the　finite　element　model　of　the　bolted　joint,　and　through　numerical　simulation,　the　state　of　the　contact　surface　of　the　tightened　bolted　connection　was　analyzed.　Increasing　the　friction　coefficient　was　shown　to　improve　the　structural　performance　of　the　bolted　joint.　The　results　provide　a　theoretical　basis　for　designing　uniform　preloading　of　bolted　joints　and　reducing　micro-slip　at　the　joint　interface.