Abstract: Infrared search and tracking systems based on the mobile platform have become the mainstream trend of the new generation in optoelectronic search and track systems, and miniaturization and lightweight guarantee high mobility. The angular velocity disturbance, coupled with the carrier's motion attitude change and internal torque disturbance of the system, raises serious challenges to the optical-axis stability control of the optoelectronic load. The traditional optic-axis stability method based on a combination of multi-axis, multi-frame, and high-precision gyro feedback control, is no longer applicable. In this study, a double-velocity closed-loop same-order cascade control method is proposed based on square PI and Luenberger disturbance observation and feedforward, for the optical axis stability control of the optoelectronic load on a two-axis two-frame mobile platform infrared search and tracking system. Simulations and experiments show that compared with the conventional single-gyro closed-loop and double-velocity closed-loop stability control methods, the proposed stability control method can effectively improve the stability accuracy of the optical axis under low-frequency disturbance of the carrier's motion. Under a disturbance of 1°/1 Hz carrier motion, the stability accuracy of the simulated optical axis improved to 2.7817 μrad and that of the actual experiment improved to 35.85 μrad. Under a disturbance of 1° /2 Hz carrier motion, the stability accuracy of the simulated optical axis improved to 38.199 μrad and that of the actual experiment improved to 119.1 μrad. Finally, using the stability control method proposed in this study, the two-axis two-frame infrared search and track system based on the mobile platform effectively overcame the low-frequency angular velocity disturbance coupled with the carrier's motion attitude change between marching, to realize a highly stable and highly dynamic optical-axis-oriented control performance of the optoelectronic load.