Abstract: Macau Science Satellite-1 (known as MSS-1) is a low-inclination mission that will be launched at the beginning of 2023. An optical bench is used for accessing high-precision strength and direction measurements of the magnetic field. In this paper, we present a thermal stability design for the optical bench based on quasi-kinematic support by kinematic hinges on the MSS-1. The change in angles with the finite element method (FEM) model modified by thermal deformation test data is analyzed. The robustness of the structure is also investigated via the Monte Carlo method. Two main results are obtained. First, the peak-to-peak value (Vp-p) of the inter-boresight angle is at most 1.24″, and the Vp-p of the inter-boresight angle modification and analysis is no more than 3.13″, both of which are better than those on the Swarm satellites in orbit. Second, the 90° fibers of the carbon-reinforced arm need to be strictly controlled during the technological process.