In order to improve the control accuracy of flexible manipulator,a combined control method based on sliding mode control and optimal control was proposed.The dynamic model was constructed by Lagrange method and hypothetical mode method,and then the flexible arm was decoupled by singular perturbation theory to obtain slow and fast varying subsystems.For the slowly varying subsystem,the sliding mode control was used to realize trajectory tracking,a new reaching law was proposed.Based on the power reaching law,the variable speed reaching term was added,the system state variable was introduced,the reaching rate was dynamically adjusted,the exponential term was added to improve the reaching speed,and the hyperbolic tangent function was used to replace the symbolic function to suppress chattering.For the fast varying subsystem,the optimal control was used to suppress the vibration.MATLAB simulation results show that the combined control method has better dynamic performance and robustness than pure sliding mode control.