The invention discloses a reusable vehicle reentry section robust fault-tolerant guidance system and a working method, relates to the technical field of aerospace, can avoid the problems of partial failure, saturation and uncertainty of an actuator control surface in a reusable vehicle reentry gliding process, and has good robust fault-tolerant performance and control precision. According to the system and method, a nonlinear disturbance observer of an attitude angle loop and an angular rate loop and an improved prediction correction guidance law are adopted, the observer is based on the principle of a fast arc tangent tracking differentiator, and the prediction correction guidance law introduces a gain compensation term into a quasi-balanced gliding condition. Besides, an anti-saturationauxiliary structure suitable for a multiple-input-multiple-output system is adopted, variables in the auxiliary structure are introduced into a backstepping method to design a robust fault-tolerant control strategy, and finally closed-loop stability of the system is guaranteed through a Lyapunov method.