Abstract: During the on-orbit period, the optical performance of the space solar telescope (SST) in the space environment will be affected by the extreme temperature variations. The quality of the image will become poor, and the resolution could be lowered. So the thermal-optical test in the simulation environment is important for SST development. This paper discusses some thermal-optical tests for SST and cryogenic optical facilities in other countries, and makes some suggestions about SST development in China.