Power switching method for hypersonic lifting body aircraft and aircraft

The invention provides a power switching method for a hypersonic lifting body aircraft, which comprises the following steps that: during the boosting of an aircraft, external air enters from an inlet of an internal flow passage of the aircraft, partial air is discharged from an outlet of the internal flow passage of the aircraft, and the other air is discharged downward with a fixed inclination angle at an inlet section of the internal flow passage. The invention also provides the hypersonic lifting body aircraft for realizing the power switching method, lip cover plates of the aircraft have a fixed lip cover plate and a sliding lip cover plate, and the lip cover plates are both provided with a group of gaps which are alternately arranged, and can relatively slide under the control of a linear motor to form a plurality of aerial drainage seams which can quickly be opened and closed below the internal flow passage. The aerial drainage seams are completely opened at a boosting stage, and are completely closed w