Abstract: Space-based infrared detection systems for space targets are affected by strong stray light from the Earth and atmosphere outside the field of view when detecting faint targets in low Earth orbit. Therefore, such detection systems have high requirements for stray light suppression. Based on the requirements of space-based infrared detection for space targets, this study analyzes the stray light suppression technologies of several foreign space-based infrared detection systems, investigates the stray light suppression technology of coaxial optical systems used for space-based infrared detection of space targets, and proposes a technical approach to further improve stray light suppression by adding a center baffle to the back of the secondary mirror. Using SABER's coaxial optical system as an example, the stray light suppression capability was simulated before and after adding the center baffle. The simulation results show that, after adding the center baffle to the back of the secondary mirror, the point source transmittance (PST) of the optical system in the detection direction at the edge is significantly reduced by 46% and 35% when the off-axis angles are 5° and 10°, respectively.