In the re-entry phase of Reusable Launch Vehicles (RLVs),there are unknown disturbances, uncertainty and Partial Effectiveness Loss Fault (PELF) of control surfaces.To solve the problems,a robust fault-tolerant control system is designed based on Incremental Backstepping (IBS) and Tracking Differentiator Disturbance Compensator (TDDC).Firstly,IBS control laws are designed for the loops of attitude angles and angular rate respectively,and an error integral term is introduced to enhance the robustness of the system.Secondly,a TDDC based on Sigmoid function applicable to IBS control laws is constructed to estimate and compensate for the slow variable terms and high-order terms after Taylor expansion,which are omitted by the traditional IBS.Finally,the simulation results show that the control laws presented here have higher command tracking accuracy than the traditional IBS.