Due　to　the　complexity　of　the　geological　environment　and　the　lack　of　research　on　the　adaptability　of　shield　tunnel,　it　is　difficult　to　build　a　tunnel　in　the　coastal　area　of　complex　stratum.　Duetothe　improper　selection　of　shield,　unadaptive　phenomena　such　as　shutdown　and　hardtunneling　occur　from　time　to　time.　Under　complex　geological　conditions,　shield　construction　often　faces　the　influence　of　many　uncertain　factors,　which　is　difficult　to　carry　out　effective　and　quantitative　evaluation.　Based　on　this,　a　shield　tunnel　adaptability　evaluation　method　based　on　fuzzy　comprehensive　evaluation　model　and　analytic　hierarchy　process　(AHP)　was　proposed.　Firstly,　based　on　the　comprehensive　analysis　of　the　influencing　factors　of　shield　type　selection　adaptability　under　the　condition　of　coastal　complex　stratum,　five　evaluation　indexes　that　can　fully　reflect　the　difference　of　geological　adaptability,　representative　and　high　discrimination　were　selected,　and　the　evaluation　index　system　of　shield　type　selection　adaptability　was　constructed.　The　improved　genetic　algorithm　(IGA)　and　AHP　(IGA-AHP)　were　introduced　to　determine　the　hierarchical　single　ranking　weight　and　hierarchical　total　ranking　weight　of　the　evaluation　index,　which　overcame　the　defects　of　AHP　in　consistency　test.　Secondly,　the　membership　function　of　each　evaluation　index　was　constructed　by　fuzzy　mathematics,　the　membership　matrix　of　shield　selection　was　obtained,　and　then　the　fuzzy　comprehensive　evaluation　model　of　shield　selection　adaptability　under　the　condition　of　coastal　complex　stratum　was　determined.　Finally,　taking　the　section　from　Pengcuo　north　station　to　Caicuo　station　of　Xiamen　rail　transit　line　4　as　an　example,　the　rationality　and　accuracy　of　the　constructed　fuzzy　comprehensive　evaluation　model　for　shield　selection　adaptability　were　verified.　The　evaluation　results　are　in　line　with　the　actual　situation,　which　provides　a　certain　reference　for　shield　selection　in　similar　strata　in　the　future.　©　2022,　Central　South　University　Press.　All　rights　reserved.