It　is　known　that　mechanical　connections　have　great　nfluence　on　the　dynamic　characteristic　of　the　assembly.　In　xisting　methods,　the　torsional　stiffness　of　the　robotic　joint　is;alculated　only　considering　the　stiffness　of　components　of　the;ystem,　which　largely　reduces　the　prediction　accuracy　of　the　oint　stiffness.　In　the　paper,　to　predict　the　joint　stiffness　more　accurately,　a　model　is　proposed　considering　influences　of　the;tiffness　of　all　connections　existed　in　a　joint　system.　The　normal　Lnd　tangential　stiffness　of　the　contact　surface　of　each　connection　re　calculated　by　combining　the　equilibrium　analysis　of　the　force　and　the　fractal　theory.　Then　the　total　stiffness　of　one　robotic　joint　:an　be　modelled　by　putting　the　torsional　stiffness　of　all　:onnections　and　that　of　the　RV　reducer　and　gear　pair　in　parallel.　Co　verify　the　proposed　model,　its　simulation　result　is　compared　o　the　stiffness　based　on　the　previous　technique　without;onsidering　the　influence　of　connections.　The　comparison　result　hows　that　the　proposed　model　can　improve　the　stiffness)rediction　accuracy.　This　study　can　be　extended　to　the　stiffness　nodeling　of　other　joint　systems　and　provides　a　theoretical　basis　br　the　dynamic　analysis　of　the　robotic　system.