Abstract: For a single channel rolling missile, the autopilot structure was constructed in body coordinate system. By rolling transfer of coordinate system, the structure loop was transferred to quasi-body coordinate system and was simplified. Then the autopilot structure was designed in quasi-body coordinate system. It is notified that the cross couplings between the vertical and lateral motion exist in the autopilot loop of quasi-body coordinate system. To eliminate the cross couplings, decoupling control of autopilot loop was implemented by means of series compensation. Simulation results prove that the design method presented in this article is feasible.