During the observation of the ground by the space optical system, stray radiation will enter and degrade the imaging quality of the optical system. In order to improve the imaging effect of the system, this paper takes the front optical system of an AOTF imaging spectrometer as an example, designs and builds a truss optical machine structure in Pro/E, and completes the optical machine modelling in Trace Pro. The stray light paths were analysed by ray tracing simulation and the important surfaces of the optical machine were identified. The design of external hood and light-blocking rings and the design of the light baffle and the alienated inner hood were carried out respectively. Numerical calculations of PST curves for off-axis angles from 5 °to 80 °were carried out for each of the three cases by ray tracing without stray light suppression, using only external hood suppression, and using internal and external suppression measures. After comparative analysis, it was determined that the PST value for the use of all strays light suppression measures at an angle greater than 30°was less than the stray light level target value of 10 -7 by two orders of magnitude and less than the PST of the optical machine without stray light suppression by four orders of magnitude, verifying that the stray light suppression method in the paper works well. INTRODUCTIONStray light refers to non-imaging light other than imaging light, through normal or abnormal methods to the image plane. Space optical systems generally operate in a very complex environment, where radiation sources such