In　this　article,　a　comprehensive　geometrical-mechanical-thermal　predictive　model　is　developed　for　thermal　contact　conductance　between　two　flat　metallic　rough　surfaces.　The　rough　surface　was　characterized　by　Weierstrass-Mandelbrot　fractal　function.　The　micro-morphology　was　measured　by　laser　microscope　to　identify　the　fractal　parameters　that　were　then　applied　to　mechanical　and　thermal　modeling.　A　new　contact　mechanics　model　was　then　proposed　to　calculate　the　contact　parameters,　and　different　contact　scales　between　asperities　and　three　modes　of　deformation,　elastic,　elastic-plastic　and　fully　plastic,　were　taken　into　account.　The　normal　contact　pressure,　which　should　be　equal　to　the　exterior　load,　was　formulated　as　a　function　of　the　fractal　parameters,　the　maximum　contact　area　and　the　material　physical　properties　of　the　given　surface.　Based　on　the　contact　mechanics　model,　first　a　single　pair　of　contacting　asperities　was　proposed　and　then　multi-contacting　asperities　were　combined　to　get　total　thermal　contact　conductance.　The　influences　of　contact　load,　surface　roughness,　asperity　top　radius　and　contact　area　as　well　as　the　temperature　on　the　thermal　contact　conductance　were　investigated　by　using　the　proposed　model.　The　investigation　results　showed　that　thermal　contact　conductance　increases　with　the　contact　load　and　contact　area.　The　larger　the　surface　roughness,　the　smaller　is　the　thermal　contact　conductance.　Finally,　the　experiments　were　conducted　to　validate　the　effectiveness　of　the　thermal　contact　conductance　modeling.　This　geometrical-mechanical-thermal　predictive　model　was　compared　with　the　two　existing　predictive　models　and　a　series　of　experimental　data.　The　results　showed　good　agreement,　demonstrating　the　validity　of　the　model　and　providing　certainty　for　further　study　on　the　heat　transfer　between　contact　surfaces.