The　bay　area　contains　terrestrial　forests　and　coastal　mangroves　with　vital　ecosystem　functions,　which　provide　essential　ecosystem　services　such　as　carbon　sequestration　and　biodiversity　maintenance.　Meanwhile,　the　bay　area　usually　hosts　intensive　socioeconomic　activities.　High-intensity　anthropogenic　activities　in　the　bay　area　have　threatened　the　terrestrial　ecosystem　and　marine　environment.　Harmonizing　the　relationship　between　terrestrial　ecosystem　conservation,　marine　environmental　governance,　and　socioeconomic　development　is　crucial　for　realizing　the　national　“coordinated　land　and　marine　development”　strategy　and　promoting　sustainability　in　the　bay　area.　This　study　constructed　a　coupling　coordination　assessment　system　of　the　terrestrial　ecosystem,　marine　environmental　system,　and　socioeconomic　system.　Taking　the　bay　area　of　the　Fujian　River　Delta　as　a　case　study,　multiple　ecological　models　were　integrated　to　quantify　the　coupling　coordination　degree　between　these　three　systems　and　present　its　spatial　distribution　characteristics.　Furthermore,　the　constraint　types　on　the　coupling　coordination　degree　were　spatially　revealed　in　the　bay　area.　The　results　suggested　that　there　are　significant　spatial　differences　in　the　coupling　coordination　degree　of　the　three　systems　in　the　bay　area　of　the　Fujian　River　Delta.　The　areas　with　a　relatively　low　coupling　coordination　degree　are　mainly　focused　on　the　central　part　of　the　Xiamen　Bay　area　and　the　southeastern　part　of　the　Quanzhou　Bay　area.　Regions　with　high　socioeconomic　development　tend　to　present　weak　terrestrial　or　marine　eco-environmental　conditions.　The　critical　constraint　factor　of　the　coupling　coordination　degree　in　the　Zhangzhou　Bay　area　is　its　backward　socioeconomic　development　level.　The　backwardness　of　both　the　terrestrial　ecosystem　and　marine　environmental　system　exists　in　most　districts　of　the　Xiamen　Bay　area.　In　addition,　the　marine　environmental　conditions　in　the　Xiamen　Bay　area　are　worse　than　those　in　the　Quanzhou　Bay　Area　and　the　Zhangzhou　Bay　area.　©　2024　by　the　authors.