Abstract: In order to improve the stealth performance and maneuverability of the aircraft exhaust system, this paper proposes a bionic dragonfly vertical takeoff and landing nozzle, whose flow characteristics and optimization under different modes are investigated. The Computational Fluid Dynamics approach is used to simulate the flow fields of this nozzle in the cruise, S-type stealth, and vertical takeoff and landing modes. Based on the analyses of the obtained flow fields in each mode, the effects of the relative angle between adjacent nozzle sections on the nozzles's aerodynamic characteristics in the S-type stealth mode and the vertical takeoff and landing mode were studied, yielding an optimized combination of the relative angles for each mode. The results show that, under the same condition, the conventional cruise-mode nozzle has a better aerodynamic performance; the relative angle of adjacent nozzle sections significantly impacts on the aerodynamic performance of the nozzle. The overall aerodynamic performance of the S-type stealth mode nozzle with an angle combination θ₁ = −34°, θ₂ = 12° and θ₃ = 22° and the vertical takeoff and landing mode nozzle with θ₁ = 35°, θ₂ = 30° and θ₃ = 30° are better.