The rotor-rotor interactional effects cause complex and highly unsteady flow fields around neighboring rotors, which are directly related to the aerodynamic performance and noise generation of the multirotor UAV. The rotor-rotor interaction is significantly affected by the separation distance between adjacent rotor tips. In this paper, the effects of adjacent rotor tip distance on the aerodynamic noise characteristics of quadrotor systems are investigated. In this paper, the effects of adjacent rotor tip distance on the aerodynamic noise characteristics of quadrotor systems were investigated by using a tool for calculating the aerodynamic noise characteristics of rotating system have built based on combining the unsteady panel method and acoustic analogy on the basis of solving the FW-H equation base on Najafi’s formulation 1C.