Application　of　amidoxime　(AO)　based　fibrous　adsorbents　in　uranium　extraction　from　seawater　(UES)　is　hampered　in　their　adsorption　performance　and　preparation　process,　including　two　items:　firstly,　low　grafting　kinetics　of　monomer　acrylonitrile　(AN)　and　large　amount　of　its　homopolymers,　secondly,　low　extraction　efficiency　limiting　by　the　ultralow　concentration　of　uranium　and　temperature　of　seawater.　Herein,　an　ultrafast　strategy　to　prepare　AO　based　nanofibers　(NFs)　with　polyvinyl　alcohol　(PVA)　super　hydrophilic　slit　nanopore　structure　via　radiation　crosslinking　and　grafting　polymerization　(c-PVA-g-PAO　NFs)　was　designed.　Combined　with　hydrophilic　2D　MXene　nanosheets　for　excellent　photothermal　and　photoelectric　synergistic　assistance,　further　improved　the　adsorption　performance　of　the　material　(c-PVA-g-PAO　&　MXene　NFs).　Super　hydrophilic　PVA　NFs　with　water-resistant　three-dimensional　network　structure　generated　by　radiation　crosslinking　realized　ultrafast　graft　poly-merization　of　AN.　Within　1　min　AN　can　be　grafted　throughout　the　c-PVA　NFs　in　its　aqueous　solution　with　degree　of　grafting　(DG)　73.71%,　and　construct　a　well-developed　slit　nanopore　structure　inside　and　outside　of　the　fiber.　Through　ultrasound,　MXene　can　be　effectively　loaded　on　the　surface　of　the　nanofiber,　and　further　enhance　30.16%　of　the　adsorption　capacity　of　the　material　under　light　with　MXene　content　8　wt%.　The　c-PVA-g-　PAO　&　MXene　NFs　achieved　adsorption　capacity　of　uranium　with　2.23　mg/g　in　natural　seawater　for　1　week,　which　increased　26.70%　than　in　dark　(1.76　mg/g).　And　it　could　undergo　at　least　5　cycles　of　adsorption　and　elution.　This　novel　strategy　with　ultrafast　grafting,　facile　operating　process　and　solar-induced　synergy　provided　a　new　ideal　to　promote　the　industrialization　process　of　UES.