Permeation　of　graphene　oxide　(GO)　membranes　is　expected　to　improve　significantly　when　epoxy　groups　are　removed　while　retaining　hydroxyl　groups　in　the　GO　flakes.　However,　it　is　still　difficult　for　conventional　reduction　methods　to　achieve　such　selective　reduction　of　oxygen-containing　groups.　In　this　paper,　we　demonstrated　the　precise　selective　reduction　of　GO　flakes　with　low　epoxy　content　but　high　hydroxyl　content　using　modified　electron　beam　irradiation　(EBI).　Remarkably,　membranes　prepared　with　the　reduced　GO　flakes　(EBI-rGO)　have　ultrahigh　water　permeation　from　92.7　to　267.1　L　m(-2)　h(-1)　bar(-1)　while　still　maintaining　the　effective　rejection　rates　for　both　dyes　(methyl　blue,　pararosaniline　and　rhodamine　B)　and　multivalent　metal　ions　(Fe3+,　Pb2+　and　Cu2+).　Theoretical　calculations　show　that　newly　generated　hydroxyl,　obtained　by　reducing　epoxy　using　the　hydrogen　radical　(H　center　dot),　plays　an　important　role　in　controlling　selective　reduction.　Our　study　provides　an　effective　way　to　fabricate　GO　membranes　with　outstanding　water　purification　performance.　(C)　2020　Elsevier　Ltd.　All　rights　reserved.