A　persistent　ultrasound-assisted　hydrothermal　method　has　been　developed　to　prepare　cobalt　oxide　incorporated　nitrogen-doped　graphene　(Co3O4/N-GO)　hybrids.　The　electrochemical　behaviors　and　catalytic　activity　of　the　prepared　hybrids　have　been　systematically　investigated　as　cathode　materials　for　Al-air　battery.　The　results　show　that　ultrasonication　can　promote　the　yield　ratio　of　Co3O4　from　63.1%　to　70.6%.　The　prepared　Co3O4/N-GO　hybrid　with　ultrasonication　exhibits　better　ORR　activity　over　that　without　ultrasonication.　The　assembled　Al-air　battery　using　the　ultrasonicated　Co3O4/N-GO　hybrid　exhibited　an　average　working　voltage　of　1.02　V　in　4　M　KOH　electrolyte　at　60　mA.cm(-2),　approximately　60　mV　higher　than　that　using　hybrid　without　ultrasonication.　This　should　be　attributed　to　large　number　density　of　fine　Co3O4　particles　growing　on　the　dispersed　GO　sheets　under　the　persistent　ultrasonication.　The　related　ultrasonic　mechanism　has　been　discussed　in　details.