Combined with a strapdown inertial navigation technology, the effect of the technical parameters of a rudder on the performance of a roll autopilot was studied systematically. According to the roll-loop characteristics, the relationship between the roll-loop cut-off frequency and the rudder bandwidth was analyzed; and by comparing the simplified low-order model with the high-order model, the effect of the rudder bandwidth and phase angle on the roll-loop performance was studied based on a frequency domain analysis. In the step response form of a second-order system, the maximum angular velocity of the rudder was determined in combination with the downwash torque with the rolling steady-state command, which ensures the roll autopilot to operate on a linear area under the condition of maneuvering flight. Furthermore, considering the second-order system rudder model with the restrictions on angular velocity and angles and the maximum disturbing torque under different total attack angles, the roll-loop commands and the response state of roll in a saturated nonlinear area was examined,and the stability of roll-loop was proved. Experimental results show that the rudder bandwidth should be no less than 20 Hz and the damping ratio should be 0.6 or more when the missile time constant is 0.3 s, rudder surface moment efficiency is 42 N·m/rad,and the bandwidth of the roll autopilot needs to be more than 50 rad/s.