This paper proposes an optimized continuous non-singular terminal sliding mode (NTSM) control scheme for a class of two-link flexible manipulators with uncertain model parameters. Firstly the original system is transformed into the controllable minimum phase system using output redefinition with purpose to change its non-minimum phase dynamics and the corresponding input-output subsystem and zero dynamic subsystem can be obtained. Then a novel continuous NTSM controller by combining NTSM and high order sliding mode (HOSM) on the basis of relative degree and a genetic algorithm is designed to obtain its optimal control performances, respectively. Simulation results illustrate the correctness of the proposed scheme.