The　nonuniform　cantilever　beam　and　Hertzian　contact　model　have　been　widely　used　to　derive　the　mesh　stiffness　of　spur　gear　assuming　that　the　contact　surface　is　absolutely　frictionless.　However,　studies　have　confirmed　that　machined　surfaces　are　rough　in　microscale　and　can　be　simulated　by　the　Weierstrass-Mandelbort　function.　In　order　to　get　a　reasonable　and　precise　mesh　stiffness　model,　the　M-B　contact　model　and　finite　element　method　are　combined　to　express　the　local　contact　stiffness　K-h.　Through　the　simulation　and　comparison,　the　analytical　finite　element　method　is　proved　to　be　consistent　with　the　traditional　models　and　introduces　the　roughness　parameters　of　machined　tooth　surface　into　the　meshing　process.　Furthermore,　the　results　also　show　that　it　is　advantageous　to　improve　the　total　mesh　stiffness　by　increasing　the　fractal　dimension　D　and　input　torque　T　as　well　as　decreasing　the　roughness　parameter　G.　In　this　paper,　a　relationship　is　built　between　the　total　mesh　stiffness　of　gear　sets　with　tooth　surface　characters　and　input　torque,　which　can　be　a　guidance　in　the　design　of　the　tooth　surface　parameters　and　the　choice　of　the　processing　method　in　the　future.