For an image-based tracking loop system of tip-tilt mirror, the traditional control methodologies mainly include a single-position loop or two-position loop. The most effective method for enhancing tracking performance is to increase control gain for a high bandwidth. However, the image sensor sampling rate and time delay engendered by data processing restricts the bandwidth. Therefore, a position-rate control method is proposed to improve the performance of a tip-tilt mirror control system. The angular rate of tip-tilt mirror is calculated from the angular position measured by the linear encoder. The open-loop rate transfer function of tip-tilt mirror features differential in the low-frequency domain because the original tip-tilt control system is zero-type. When the inner rate feedback loop is implemented, an integrator is introduced into the original position loop. A PI (proportional-integral) controller can stabilize the position loop such that two integrators are in the tracking loop, so the low-frequency performance can be improved compared to the original control method. The experimental results coincide with the theoretical analysis and then verify the correctness of the presented theories.