Polyaniline　(PANI)-based　composite　materials　have　shown　to　be　promising　candidates　for　oxygen　evolution　reaction　(OER)　electrocatalysts　because　of　their　non-ignorable　merits　of　conductivity,　flexibility,　durability　and　environmental　friendly.　Herein,　we　develop　a　facile　strategy　to　realize　in-situ　assembly　of　CoOOH　nanosheets　into　the　PANI　network,　which　is　denoted　as　Co/PANI　HNSs　for　OER　performance.　The　nitrogen　species　derived　from　PANI　building　blocks　can　work　as　bridging　sites　to　preferentially　coordinate　with　Co　metal　ions,　which　impart　coupling　effects　between　CoOOH　nanosheets　and　PANI　as　well　as　the　structure　stability.　Besides　the　Co-N　coordination,　the　occurred　electron　delocalization　between　Co　d-orbitals　and　PANI　π-conjugated　ligands　can　also　modulate　the　electronic　structural　states　of　Co/PANI　HNSs,　enabling　the　efficient　interfacial　electron　transfer　from　CoOOH　to　PANI.　In　addition,　the　Co/PANI　HNSs　possesses　a　hierarchical　porous　with　both　structure　of　mesopores　and　macropores　that　allows　electrolyte　to　be　more　efficiently　transported　to　the　highly　oxidative　active　sites,　resulting　in　fast　reaction　kinetics.　In　recognition　of　these　advanced　structural　characteristics,　the　Co/PANI　HNSs　electrocatalyst　can　give　a　low　overpotential　of　291　mV　at　an　anodic　current　density　of　10　mA　cm−2　and　a　small　Tafel　slope　of　54　mV　dec−1　in　1　M　KOH　electrolyte　as　well　as　a　good　durability.　©　2020