<p>Spaceborne Synthetic Aperture Radar (SAR) operating in the squint sliding spotlight mode is critical for achieving high-resolution imagery, as its imaging performance relies fundamentally on precise beam steering control. Conventional methods, depending either on frequent satellite attitude maneuvers or on full two-dimensional electronic antenna scanning, are generally accompanied with high system complexity and cost. To address these challenges, this paper proposes a coordinated control method for satellite attitude and antenna beam steering that performs joint optimization over five control variables: the satellite’s three-dimensional attitude (yaw, pitch, roll) and the antenna’s two-dimensional steering (azimuth, elevation). The approach begins with the construction of a system model that integrates SAR imaging geometry, radar signal characteristics, and engineering constraints. The core optimization objective is defined as minimizing the range-variant Doppler centroid, from which the optimal five-dimensional control variables are solved. Subsequently, an engineering-feasible joint control law compliant with the satellite’s attitude maneuverability constraints is derived. Simulation results confirm the effectiveness of the proposed method. This work provides key technical support for the mission planning and control system design of high-performance SAR satellites.</p>