China　has　many　bridges　in　a　vulnerable　condition,　and　strengthening　is　crucial　to　guarantee　their　service　life　and　performance.　However,　environmental　impact　is　rarely　considered　in　the　maintenance　of　reinforced　concrete　structures.　Moreover,　considering　the　effects　of　vehicle　overload　and　the　external　environment　remains　difficult.　To　solve　these　problems,　the　life-cycle　reliability　and　induced　environmental　impact　of　strengthening　bridges　with　bonded　carbon-fibre-reinforced　polymer　under　different　external　environmental　conditions　and　overload　scenarios　were　studied　using　Monte　Carlo　sampling,　first-order　second　moment　and　life-cycle　assessment　methods.　A　simply　supported　reinforced　concrete　T-beam　was　selected　as　a　case　study.　The　results　indicated　that　the　external　environmental　conditions　contributed　significantly　to　the　polymer　strengthening　effect,　and　polymer　plates　contributed　more　to　reliability　than　polymer　fabric.　In　overload　scenarios,　plates　were　more　suitable　for　strengthening　than　fabric.　When　annual　environmental　impacts　were　considered　over　time,　life-cycle　maintenance　plans　with　plates　were　better　than　with　fabric,　and　environmental　impacts　were　sensitive　to　the　discount　rate.　©　2021　ICE　Publishing:　All　rights　reserved.