Fiber　reinforced　polymer　(FRP)-reinforced　seawater　sea-sand　concrete　(SSC)　structures　are　prospective　substitutions　for　traditional　steel-reinforced　concrete　structures,　especially　in　maritime　environment.　To　demonstrate　the　feasibility　of　the　FRP-reinforced　SSC　structures,　an　in-depth　understanding　on　the　bond　strength　of　glass　FRP　(GFRP)　bars　to　SSC　under　pull-out　loading　is　essential.　In　this　regard,　pullout　tests　on　45　specimens　with　a　10　mm　diameter　GFRP　bar　embedded　in　ultra-high　strength　concrete　(including　normal　concrete　with　river-sand　and　fresh　water　and　SSC)　are　conducted　in　this　study.　Particularly,　the　experimental　tests　focus　on　some　key　factors　that　governing　the　GFRP　bars　in　concrete,　such　as　the　bar　embedment　length,　the　polyethylene　(PE)　fiber　volume　fraction,　and　the　concrete　strength　(i.e.,　80　MPa　and　120　MPa).　Three　major　failure　mechanisms　and　two　types　of　average　bond　stress-slip　curves　are　obtained　from　the　tests.　The　results　show　that　substitution　of　seawater　and　sea　sand　for　normal　concrete　has　no　distinct　effect　on　short-term　change　in　bond　strength　(less　than　9%).　In　addition,　it　indicates　that　the　increase　in　concrete　strength　and　PE　fiber　content　could　improve　the　bond　strength,　whereas　increasing　the　embedment　length　(from　2.5　times　to　10　times　of　bar　diameter)　could　result　in　a　decrease　in　bond　strength　(by　20-30%).　Furthermore,　it　demonstrates　that　the　CMR　model　has　better　performance　than　the　mBPE　model　in　capturing　the　experimentally　observed　ascending　part　of　the　bond-slip　curve.