Abstract: The all attitude control and velocity track of helicopter with actuator saturation constraints was considered. A two-step anti-windup control approach was proposed, which can be applied to open-loop unstable systems such as helicopter. Without consideration of saturation constraints, H_∞ loop shaping inner and outer loop controller was given. The inner loop achieved all attitude control and channels decoupling, while the outer loop realized velocity tracking. With consideration of saturation constraints, the design of anti-windup compensator was proposed to reduce close-loop performance degradation caused by saturation. L₂ stability of the proposed anti-windup control system was proved, and give potentially less conservative of anti-windup compensator by loop transformation and multiplier theory. The simulations of UH-60 Black Hawk helicopter show the effectiveness of the proposed anti-windup control method.