The　Antarctic　continent　has　extreme　natural　environment　and　fragile　ecosystem.　Mosses　are　one　of　the　dominant　floras　in　the　Antarctic　continent.　However,　their　genomic　features　and　adaptation　processes　to　extreme　environments　remain　poorly　understood.　Here,　we　assembled　the　high-quality　genome　sequence　of　the　Antarctic　moss　(Pohlia　nutans)　with　698.20　Mb　and　22　chromosomes.　We　found　that　the　high　proportion　of　repeat　sequences　and　a　recent　whole-genome　duplication　(WGD)　contribute　to　the　large　size　genome　of　P.　nutans　when　compared　to　other　bryophytes.　The　genome　of　P.　nutans　harbors　the　signatures　of　massive　segmental　gene　duplications　and　large　expansions　of　gene　families,　likely　facilitating　neofunctionalization.　Genomic　characteristics　that　may　support　the　Antarctic　lifestyle　of　this　moss　comprise　expanded　gene　families　involved　in　phenylpropanoid　biosynthesis,　unsaturated　fatty　acid　biosynthesis,　and　plant　hormone　signal　transduction.　Additional　contributions　include　the　significant　expansion　and　upregulation　of　several　genes　encoding　DNA　photolyase,　antioxidant　enzymes,　flavonoid　biosynthesis　enzymes,　possibly　reflecting　diverse　adaptive　strategies.　Notably,　integrated　multi-omic　analyses　elucidate　flavonoid　biosynthesis　may　function　as　the　reactive　oxygen　species　detoxification　under　UV-B　radiation.　Our　studies　provide　insight　into　the　unique　features　of　the　Antarctic　moss　genome　and　their　molecular　responses　to　extreme　terrestrial　environments.