The invention relates to a mechanical-thermal control coupling design method based on a quasi-equilibriumgliding principle. The method comprises the following steps: on the basis of the quasi-equilibriumgliding principle, establishing a reentry vehicle kinetic model by utilizing the assumption that local trajectory inclination anglechange rate and local trajectory inclination angle are approximate to zero; converting mechanical-thermalconstraint into flight corridor constraint; optimizing by taking a heeling angel as a single variable; controlling a flight path within a flight corridor, thereby meeting the mechanical-thermal requirement and the voyage requirement. According to the invention, the constraint conditions, such as, heat flow and overload, are converted into a boundary of an equivalent lift-drag ratio and the mechanical-thermal control compact coupling design is realized through the equivalent lift-drag ratio, so that the overall performance of the gliding aircraft is promoted and the problems of mutual restriction of mechanical-thermal control and difficulty in coupling design can be solved.