For the aerodynamic performance optimization problem of a tilt-rotor quadcopter UAV caused by rotor configuration changes in multi-rotor mode and fixed-wing mode, a parametric CFD（Computational Fluid Dynamics） model was established to systematically analyze the influence of different rotor spacings on flow field structure, lift distribution, hover power, and lift characteristics during level flight. Based on the overset grid and sliding mesh methods, unsteady simulations were conducted to investigate the aerodynamic interference characteristics between rotors at different spacings. The results indicate that excessively small rotor spacing leads to strong downwash interference, causing power loss and efficiency reduction, while excessively large spacing increases structural weight and affects aerodynamic coupling during fixed-wing flight. It is demonstrated that a reasonable rotor configuration enhances the aerodynamic characteristics of the tilt-rotor quadcopter UAV. The findings provide theoretical significance and research value for optimizing the overall parameters of UAVs and improving their flight performance.