Joined-wing configuration has lower structural weight, higher torsional/flexural strength, smaller induced drag, bigger lift coefficient, and better stability than the normal one. The purpose of this paper is to provide an effective numerical simulation method for calculation and analysis of aerodynamic characteristics of a canard joined-wing UAV. The whole research process of the UAV based on commercial software ANSYS consists of grid modeling, simulations of the flow field of the UAV, qualitative and quantitative analyses of the aerodynamic data. By means of exploring the longitudinal, lateral and directional stability of the UAV, control devices efficiency, we can finally achieve the evaluation of the UAV flight performance. According to preliminary evaluation of the UAV flight performance, we can well complete the design modifications before trial production of the UAV. In addition, the preliminary design optimization of the UAV based on the numerical simulation results will greatly shorten the overall design time, and reduce research costs of the UAV. This present work is helpful for the future aerodynamic analysis of joined-wing UAVs.