The invention discloses a method for trimming a fixed-wing airplane with a high lift-drag ratio. By adopting positively bent wing with the high lift-drag ratio, under the condition that the lift-drag ratio of the whole airplane is not reduced by using a flat tail or a canard, the wing can be trimmed with zero lift torque, so that the characteristics of the high lift-drag ratio of the positively bent wing are fully exerted; in order to make the wing be trimmed with zero lift torque and not reduce the lift-drag ratio of the whole airplane, a designed layout that the gravity is arranged under a focal point of the wing is adopted, so that the high lift-drag ratio and nose-up moment are produced to trim nose-down moment of the positively bent wing; and the whole airplane has the longitudinal static stability. The lift-drag ratio of the airplane can be increased, and the whole airplane has the static stability. The fixed-wing airplane with the high lift-drag ratio comprises a wing which has a high span-chord ratio and positive bending degree and is used for supplying a lift force so as to supply the lift force to the whole airplane, an airplane body positioned under the focal point of the wing, wing supporting beams connected with the airplane body and the wing and an engine which is arranged on the airplane body and used for supplying thrust. The invention also provides a method for achieving the high lift-drag ratio of the fixed-wing airplane.