The　remarkable　characteristics　of　the　silent　flight　of　owls　provide　infinite　inspiration　for　the　low-noise　operation　of　the　rotating　impeller　machinery.　However,　how　the　characteristics　of　owl　wings,　including　the　leading-edge　serrations,　trailing-edge　serrations,　and　plumed　surfaces,　affect　the　aerodynamic　noise　has　not　been　studied　comprehensively.　According　to　previous　research,　the　noise　reduction　level　of　an　airfoil　with　an　extensive　sinusoidal　profile　is　limited　to　a　certain　degree.　In　this　paper,　as　a　new　coupling　element,　the　surface　ridge　of　owl　wings　is　added　to　the　airfoils　with　leading-edge　serrations.　Based　on　the　NACA0012　(National　Advisory　Committee　for　Aeronautics)　airfoil,　the　bionic　airfoils　with　sinusoidal,　serrated,　and　iron-shaped　leading-edge　serrations　and　surface　ridges　are　reconstructed　and　studied　to　reveal　the　noise　reduction　mechanism　of　the　coupled　elements.　The　hybrid　numerical　method　of　large　eddy　simulation　combined　with　the　acoustic　analog　equations　is　adopted　to　predict　the　far-field　acoustic　characteristics.　The　vortex　dynamic　method　is　used　to　exposit　the　noise　reduction　mechanism　of　biomimetic　flow　control.　The　results　demonstrate　that　the　airfoil　with　iron-shaped　leading-edge　serrations　has　the　best　effect　of　noise　reduction.　Relative　to　the　original　airfoil,　the　sound　pressure　level　is　reduced　by　14.3　dB.　The　change　of　streamwise　vortices　caused　by　the　biomimetic　structures　leads　the　regular　large-scale　tubular　vortices　to　separate　into　smaller　horseshoe　vortices.　In　addition,　the　correlation　coefficient　of　spanwise　is　reduced,　and　the　change　of　time-averaged　vorticity　in　the　space　field　promotes　the　attenuation　effect　of　sound　source　caused　by　sound　pressure　fluctuation　radiation.　©　2021　Author(s).