Volatile　polycyclic　aromatic　hydrocarbons　(PAHs)　in　water　and　soil　are　associated　with　status　in　the　human　body.　Development　of　simple,　efficient　detection　method　is　challenging　due　to　the　coating　could　be　attacked　by　the　abundance　of　water　in　the　direct-immersion　solid-phase　microextraction.　The　stability　of　coating　is　essential　to　the　analysis　results.　In　this　paper,　a　stable　Ni-Zn　MOF/g-C3N4　(MG　NFs)　nanoflowers　with　cavity　traps　structure　was　firstly　reported　and　acted　as　solid-phase　microextraction　(SPME)　adsorbent　for　PAHs.　Markedly　enhanced　moisture　and　acid　stability　of　the　MG　NFs　was　obtained　through　the　doping　the　hydrophobic　graphitic　carbon　nitride　(g-C3N4)　and　metal　ions　into　metal　organic　frameworks　(MOFs).　The　aperture　environment　and　ambient　environment　of　MG　NFs　were　changed　by　the　doping　of　the　Ni　and　the　g-C3N4　respectively.　The　moisture　and　acid　stability　of　MG　NFs　were　prominently　increased　under　the　dual　protection.　Compared　to　commonly　used　commercial　coatings,　the　MG　NFs　own　large　surface　area,　unique　nanoflowers　structure　and　numerous　open　metal　sites　on　the　nanosheets,　which　demonstrated　significant　extraction　superiority　for　PAHs.　The　MG　NFs　coated　fiber　was　used　for　the　SPME　preconcentration　of　PAHs　and　couped　with　GC–MS　for　detecting　PAHs.　It　presented　low　detection　limits　(0.1–3.0　ng　L−1),　wide　linearity　(0.3–5000.0　ng　L−1)　and　good　linearity　(the　correlation　coefficient　>0.9951).　The　inter-day　and　intra-day　relative　standard　deviation　(RSD)　(n　=　3)　for　three　replicate　extractions　using　one　fiber　was　3.8%–9.1%,　and　3.5%–9.2%,　respectively.　The　fiber-to-fiber　reproducibility　(n　=　3)　was　4.2–11.8%.　The　coupling　method　was　successfully　applied　in　the　analysis　of　real　water　and　soil　samples　with　satisfactory　recoveries　of　82.9–109.2%,　84.2–106.4%,　and　the　corresponding　RSDs　were　2.4–11.3%,　3.6–10.8%,　respectively.　The　results　indicated　the　effectiveness　of　NG　NFs　coated　fiber　in　further　practical　application.　©　2018　Elsevier　B.V.