Abstract: Aiming at the problem of decreased grayscale in star images captured by star sensors mounted on exo-atmospheric platforms due to particulate matter in the plume of attitude control engines, a quantitative analysis method for starlight attenuation caused by plume particles is proposed. Based on Mie scattering theory, the Mie scattering coefficients of particles in the plume are calculated, and the influence of particles with different refractive indices on the scattered light intensity coefficient is quantitatively analyzed. A model for optical radiation transmission and its impact analysis is established to quantitatively evaluate the attenuation effect of plume particles on starlight. Simulation results indicate that particle size is a key factor affecting starlight attenuation. When the particle size is 0.9 μm, the attenuation of starlight transmission by particles in the plume is most significant, with an attenuation coefficient of approximately 0.67. This study provides important technical support for the technical index demonstration, system design optimization, and algorithm performance evaluation of star sensors used in exo-atmospheric platforms.