The　axial　flow　fan,　as　a　key　part　of　the　outdoor　unit　of　air　conditioner,　has　an　important　impact　on　the　performance　of　air　conditioner.　In　order　to　reduce　the　power　consumption　and　aerodynamic　noise　of　the　outdoor　unit,　the　outer　edge　profile　with　a　depression　structure,　inspired　by　the　effective　control　of　butterfly　wings　for　airflow,　is　reconstructed　and　adopted　in　the　design　of　bionic　blades.　The　effects　of　bionic　blades　with　four　different　depression　depths　on　the　aerodynamic　performance　of　the　outdoor　unit　are　investigated　numerically.　It　is　found　that　when　the　depression　depth　is　1.9　mm,　the　aerodynamic　performance　of　the　outdoor　unit　is　the　best.　For　the　axial　flow　fan　with　the　optimal　design　blade,　the　numerical　simulation　and　experimental　test　on　the　noise　of　the　outdoor　unit　are　carried　out.　Based　on　the　experimental　results,　the　shaft　power　of　the　outdoor　unit　is　reduced　by　1%　and　the　noise　is　reduced　by　1.3　dB　when　the　bionic　blade　with　the　depression　depth　of　1.9　mm　is　adopted.　Based　on　the　numerical　results,　the　flow　characteristics　of　the　axial　flow　fan　with　the　bionic　blades　is　analyzed　and　the　noise　reduction　mechanism　of　the　depression　structure　is　revealed.　The　studied　results　show　that　the　depression　structure　with　proper　depth　at　the　outer　edge　of　the　blades　effectively　changed　the　development　and　trajectory　of　the　tip　leakage　vortex,　which　has　a　positive　influence　on　the　aerodynamic　performance　improvement　and　noise　reduction　of　the　axial　flow　fan.　©　2022　Elsevier　Ltd　and　IIR