In　order　to　study　the　aerodynamic　performance　of　the　quadrotor　with　different　rotor　spacings　in　hover,　experiments　were　performed　together　with　numerical　simulations.　For　experimental　study,　an　experimental　platform　was　designed　to　measure　the　thrust　and　power　consumption　of　the　quadrotor　with　different　rotor　spacings　(L/R　=　2.2,　2.6,　3.0,　3.2,　3.6,　and　4.0),　and　to　attempt　to　find　out　the　optimal　rotor　configuration　which　makes　the　quadrotor　have　the　best　aerodynamic　performance.　In　addition,　the　pressure　distribution,　vorticity　of　the　blade　tip,　and　velocity　vector　of　quadrotor　in　the　flow　field　were　obtained　by　Computational　Fluid　Dynamics　(CFD)　method　to　visually　analyze　the　aerodynamic　interference　between　adjacent　rotors.　By　the　comparison　of　experimental　results　and　numerical　simulations,　the　final　results　show　that　the　aerodynamic　performance　of　the　quadrotor　varies　obviously　with　the　change　of　rotor　spacing,　and　it　has　a　negative　impact　on　hover　efficiency　if　rotor　spacing　is　too　much　small　or　large.　The　rotors　pacing　at　L/R　=　3.6　with　larger　thrust　and　smaller　power　is　considered　to　be　the　best　aerodynamic　configuration　for　the　quadrotor　with　better　aerodynamic　characteristics.　Furthermore,　compared　with　the　isolated　rotor,　moderate　aerodynamic　interference　is　proved　to　help　improve　the　aerodynamic　performance　of　the　quadrotor　with　a　larger　thrust,　especially　for　a　rotor　spacing　at　L/R　=　3.6.　©　2020　by　the　authors.