Urea　oxidation　reaction　(UOR)　emerges　as　a　promising　alternative　anodic　half-reaction　to　oxygen　evolution　reaction　(OER)　in　an　electrochemical　CO2　reduction　reaction　(ECRR)　system.　Herein,　a　Ni/MnO　heterojunction　with　extraordinary　UOR　activity　is　synthesized　on　Ni　foam.　Ex　situ/in　situ　characterization　and　theoretical　calculation　reveal　that　the　outstanding　UOR　performance　of　Ni/MnO　catalyst　can　be　ascribed　to　two　successive　surface　reconstructions.　In　the　first　and　second　surface　reconstructions,　Ni(OH)(2)/MnOOH　and　NiOOH/MnOOH　heterojunctions　are　formed　on　the　catalyst　surface,　and　Mn　and　Ni　sites　serve　as　the　active　sites,　respectively.　The　heterojunctions　formed　can　enhance　UOR　activity　by　reducing　the　surface　reconstruction　potential　and　optimizing　the　adsorption　energy　of　intermediates　through　electronic　structure　modulation　and　d-band　center　regulation.　When　employed　as　the　UOR　anode　in　the　CO2　electrolyzer,　it　requires　375　mV　less　voltage　at　10　mA　cm(-2)　than　the　OER,　revealing　the　great　potential　of　applying　such　Ni/MnO　catalyst　as　the　anodic　UOR　in　an　ECRR　system　for　carbon　neutrality.