Fiber-reinforced　polymer　(FRP)-reinforced　seawater-sea　sand　concrete　(SWSSC)　is　a　new　structure　form　for　coastal　infrastructure,　especially　for　island　construction.　The　degradation　mechanism　of　FRP　bars　in　SWSSC　involves　water　molecules,　hydroxide　ions,　chloride　ions,　high　temperature,　and　stress.　In　general,　water　molecules　and　hydroxide　and　chloride　ions　react　with　some　ingredients　in　FRP　bars,　destroy　the　interface　between　fiber　and　resin,　and　reduce　the　properties　of　FRP　bars.　In　the　environment　of　water　molecules,　hydroxide　ions,　and　chloride　ions,　the　strength　retentions　of　FRP　bars　were　71%-77%,　26%-98%,　and　49%-77%,　respectively,　depending　on　composition　and　manufacturing　techniques　of　fiber.　High　temperature　and　stress　accelerate　the　degradation　of　FRP　bars.　Under　different　temperatures　and　stress　levels,　the　strength　retentions　of　FRP　bars　were　0.6%-98%　and　43%-93%,　respectively,　depending　on　the　fiber　type,　temperature,　and　stress　levels.　The　presence　of　chloride　ions　accelerates　the　hydration　of　cement　and　improves　the　properties　of　SWSSC　at　early　age.　However,　the　conclusions　on　the　properties　of　SWSSC　at　later　age　are　still　controversial.　Based　on　previous　studies,　some　future　needs　on　FRP-reinforced　SWSSC　are　also　recommended.