Abstract: As a novel nonlinear control method, over-load control has quickly developed in the field of missile control law design in the recent years, but during the design of the skid-to-turn(STT) supersonic cruise missile pitch channel control system based on over-load control, the system exits non-minimum phase phenomena between over-load output and rudder input, that causes zero dynamic unstable. The output-redefinition method was adopted to translate system state, regard the internal states steady-state response as the expected reference trace, translate output track into state track, that guaranteed zero dynamic stable. The controller was designed by adopting second order sliding mode to eliminate inherence chatter of sliding mode control. Lyapunov function was used to determine the above controller parameter to guarantee the tracing of original system output, the attack angle observer was designed to deal with the problem of incomplete obtainable system state that was induced by attack angle uneasily measured. Simulation results show that the approach can increase robustness and stability, the system owns better dynamic performance.