The active athermalizing technique used usually in our country and the passive athermalizing technique adopted successfully overseas are described. Considering domestic conditions, the possibility of introducing the passive athermalizing is discussed from three ways, matching optical material used in the system that is all composed of spherical surfaces, using an aspherical surface and using a simple mechanical framework. Furthermore, the conclusions are given by design of a example and analysis of a great deal of data. In addition, infrared optical material, which is suitable for thermal imaging in our country now, is described.