Extracting　uranium　from　seawater　is　of　great　significance　for　ensuring　the　sustainable　development　of　nuclear　energy.　This　article　designs　a　simple　and　mass-produced　porous　sponge　polyamidoxime/polyethyleneimine　(PAO/PEI)　for　uranium　extraction　from　seawater.　The　prepared　porous　sponge　has　excellent　flexibility　and　mechanical　strength,　which　can　withstand　harsh　marine　environments.　In　a　50　mg/L　uranyl　solution,　the　maximum　adsorption　capacity　of　PAO/PEI　is　666.67　mg/g.　Moreover,　PAO/PEI　sponge　exhibits　excellent　selectivity　for　uranium　in　competitive　adsorption　conditions.　FTIR　and　XPS　are　used　to　explore　the　adsorption　mechanism,　and　the　results　showed　that　the　synergistic　effect　of　amidoxime　and　amino　groups　enhanced　the　binding　of　uranium(VI).　The　adsorption　capacity　after　15　days　of　enrichment　in　100L　natural　seawater　is　9.79　mg/g,　and　the　average　rate　is　0.653　mg/g/day.　The　results　indicate　that　PAO/PEI　porous　sponge　has　broad　application　prospects　in　large-scale　seawater　uranium(VI)　extraction.