A twin-boom UAV with inverted V-tail is proposed and compared with the existing U-tail one by numerical method. Verification and validation were made on the computational model. Longitudinal, lateral, and directional aerodynamic characteristics and static stability of the two configurations are investigated and compared, with different angles of attack and sideslip angles. The results show that the inverted V-tail can reduce the wetted area, increase the lift drag ratio of the whole aircraft by 2.2%, and increase the stall angle of attack of the tail, but the lateral static stability decreases apparently. Flow fields comparison shows that there is a great difference between the normal force position of the inverted V-tail and that of the U-tail, which is the main reason for the decrease of lateral stability. It is found that when the included angle is less than 90 degrees, the tail can enhance the lateral stability of the aircraft.