Abstract: Stray light has a significant effect on the overall performance of telescopes, particularly for infrared solar telescopes, in which internal thermal radiation causes additional stray light sources. We establish a 3-dimensional model using stray light theory and the real opto-mechanical structure of the Accurate Infrared Magnetic field measurements of the Sun (AIMS) telescope. We use the stray light ratio (i.e., the ratio of stray light energy reaching the detector to the light energy used for observations) to evaluate the imaging performance of the telescope. We analyze both thermal and non-thermal sources of stray light to comprehensively study the visible, 8–10 μm, and Fourier transform infrared systems of the telescope, finding stray light ratios of 9.31\ \times\ 10^-6 in the visible system, 2.83\ \times\ 10^-4 in the 8–10 μm system, and 1.54\ \times\ 10^-4 in the Fourier transform infrared system. This verifies that the opto-mechanical system design of the telescope can effectively suppress stray light, benefiting both imaging and magnetic field observations.