Robot-assisted　bonnet　polishing　system　(RABPS)　is　widely　used　in　the　polishing　of　optical　components　due　to　its　low　cost,　high　efficiency　and　rapid　polishing.　However,　due　to　the　insufficient　stiffness　of　the　robot,　it　is　easy　to　produce　vibration　in　the　machining　process,　which　not　only　causes　the　size　of　the　polishing　contact　area　to　deviate　from　the　ideal　value,　but　also　affects　the　removal　amount　of　workpiece.　First,　this　paper　analyzes　the　influence　of　robot　system　stiffness　on　the　actual　polishing　area　size　and　polishing　removal.　Next,　based　on　the　analysis　of　the　technical　characteristics　of　multiple　groups　of　polishing　posture　corresponding　to　the　same　point　of　robot　bonnet　polishing,　the　optimization　method　of　robot　static　stiffness　performance　is　proposed.　Finally,　the　correctness　and　efficiency　of　the　optimization　method　are　validated　by　simulation　and　experiment.　The　working　stiffness　of　the　robot　increases　by　26.8%　and　the　roughness　of　the　polished　surface　is　improved　by　42.9%　after　posture　optimization.