With　the　ever-growing　of　span　length,　the　safety　factor　of　flutter　for　long-span　bridges,　i.e.,　the　ratio　between　the　critical　flutter　wind　velocity　and　flutter　checking　velocity,　has　become　increasingly　less.　Utilizing　mechanical　devices　as　a　supplemental　measure　to　the　aerodynamic　measures　has　become　a　solution　for　enhancing　the　flutter　performance　of　long-span　bridges.　In　this　study,　the　inerter-based　dynamic　vibration　absorbers　(IDVAs),　featured　by　light-weight　and　broadband　properties,　are　employed　to　improve　the　flutter　performance　of　long-span　bridges　and　are　compared　with　conventional　tuned　mass　damper　(TMD).　A　numerical　optimal　design　method　for　the　bridge-IDVA　systems　under　flutter　is　first　proposed.　Then,　the　performance　of　the　control　systems　subjected　to　the　uncertainty　of　flutter　derivatives　as　well　as　hard　and　soft　types　of　flutter　is　systematically　investigated.　Compared　with　TMD,　utilizing　IDVAs　can　not　only　increase　the　critical　flutter　wind　velocity,　but　also　reduce　the　failure　probability　after　considering　the　uncertainty　of　flutter　derivatives.　When　the　flutter　of　a　bridge　is　characterized　by　soft　type,　the　advantages　of　the　IDVAs　will　become　more　significant.　The　findings　in　this　research　can　contribute　to　the　flutter　control　of　long-span　bridges　and　promote　the　application　studies　of　inerter-based　devices.