The static stability of missile pitching movement is one of the important performances in guidance and control systems. In this paper, a method which consists of the single and double loop longitudinal autopilot using frequency domain approach is proposed to solve the problem efficiently. Single-loop autopilot is used to simplify the system design when the missile is highly static stable; the double-loop autopilot is employed to stabilize the system and improve frequency performance when the missile is static stable or static unstable. Control gain of the system is determined by aerodynamic parameters and frequency domain indexes. The simulation result shows that double-loop autopilot based on frequency domain simplified the system design and improved the stability and robustness of missile system.