The　utilization　of　intermittent　clean　energy　requires　high　efficient　energy　storage　technologies　to　minimize　energy　losses　during　charge-discharge　processes.　In　this　work,　ionic　covalent　organic　polymer　(iCOP)　composite　membranes　are　presented　to　promote　the　battery　efficiencies　of　iron-chromium　redox　flow　battery　(ICRFB).　iCOP　powder　was　synthesized　by　interfacial　polymerization　method　and　the　resulting　composite　membrane　possessed　superior　physicochemical　membrane.　Sulfonic　acid　groups　in　the　synthesized　iCOP　facilitated　the　proton　transportation　of　the　prepared　membranes.　A　hydrogen　bond　network　formed　between　perfluorinated　PEM　and　iCOP　further　promoted　the　proton　transportation　of　the　membrane.　Meanwhile,　the　positively　charged　amino　groups　under　acidic　conditions　reduced　the　permeation　of　Fe3+　and　Cr3+　ions　due　to　the　Donnan　effect.　Specifically,　proton　conductivity　of　iCOP-8　membrane　reached　215　mS　cm(-1)　at　80　degrees　C.　Moreover,　iCOP-8　demonstrated　the　lowest　permeation　rates　for　both　Fe3+　(1.44　x　10(-7)　cm　s(-1))　and　Cr3+　(0.47　x　10(-7)　cm　s(-1))　among　all　membranes　herein.　In　terms　of　the　ICRFB　efficiencies,　a　Coulombic　efficiency　of　97.66　%　and　energy　efficiency　of　87.11　%　was　achieved　at　a　current　density　of　100　mA　cm(-2).　The　battery　also　operated　stably　for　over　200　cycles　without　significant　performance　degradation　(CE:　＞97.01　%,　EE:　＞86.01　%).