Higher, faster and drag reduction are the three eternal pursuits of aircraft design. In the optimization design of traditional fixed-wing aircraft, all kinds of flight conditions should be taken into account to seek a sub-optimal solution. The concept of variable camber wing can effectively solve this issue, which is in line with the three goals of aircraft design. In this paper, the influence of rigid deflection of trailing-edge devices on cruise aerodynamic efficiency and transonic buffeting boundary of large wide-body passenger aircraft is studied. Firstly, based on the drooped hinged flap mechanism, the combined deflection simulation program of the trailing-edge flap and the spoiler under the guidance of the mechanism was realized to automatically generate the cruising configuration with different flap deflection angles. The buffeting onset of the cruising configuration in the transonic region is obtained by unsteady CFD method. Taking the buffeting boundary as the constraint factor, and the flap deflection angle and the angle of attack as two variables, the CL-K diagram was obtained to make the optimal lift-to-drag ratio curve. In this paper, the deflection angle of the flap varies 0° to ±3° with an interval of 1° and the angle of attack ranges from -2° to 5° with an interval of 1°. The results show that the lift-to-drag ratio of the deflected configuration is higher than that of the configuration without flap deflection, and the buffeting boundary is improved by about 10%. The results show that the aerodynamic efficiency of different design points can be improved by the deflected configuration, so that the drag reduction and oil saving can be realized. The enhancement of the wing buffeting onset in the transonic region expands the flight envelope, making the aircraft fly higher and faster.