The invention provides a refrigerating-type non-heating infrared fisheye optical system, which solves the problem that the existing fisheye optical system is highly susceptible to environmental temperature changes, defocusing occurs, and imaging quality is lowered. The system comprises a front fixed lens group, an aberration correction group, a detector and a diaphragm arranged in order and fixedly connected from an object plane to a focal plane, wherein the center axes of the aberration correction group, the detector and the diaphragm are coaxial; the front fixed lens group is composed of twolenses, and the two lenses are a first negative lens and a second negative lens which are sequentially coaxial in an optical axis direction from the object plane to the focal plane; the aberration correction group comprises a first positive lens, a third negative lens and a second positive lens which are sequentially coaxial in an optical axis direction from the object plane to the focal plane; the diaphragm is coincident with a detector cold stop; the normalized thermal aberration coefficient of the second positive lens is set to be T, the T is calculated through the following formula as described in the specifications, the T needs to meet the condition of T being smaller than 5, and in the formula, n refers to the refractive index of the lens material, dn/dt is the refractive index/temperature coefficient of the lens material, and alphag is the expansion coefficient of the lens material.