The improved STT autopilot was established to decrease the sideslip angle so that the problem of roll control saturation was settled down for a gliding missile with high aspect ratio wings during big sideslip angle flight． The designed STT autopilot，other than longitudinal， yaw，and roll channels with structure similar to the traditional STT autopilot，can realize the tracking of the roll angle to the lateral acceler ation to decrease the sideslip angle by the introduction of the lateral acceleration feedback in the roll loop． The six-DOF nonlinear simula tion was performed and the results indicated that the improved autopilot effectively decreases the sideslip angle of the gliding missile during STT flight and can be used in flight control for the similar plane-symmetrical missile．