The traditional panoramic ring optical system is composed of a single lens panoramic block and a relay lens system, without an intermediate image plane and mostly used in the visible light band. It can not limit the stray light outside the imaging field of view through the field of view diaphragm, and the light can reach the image plane without reflection of the head unit or after multiple reflections in the head unit. At the same time, due to the particularity of infrared transmission materials, its application in the infrared spectrum will face a series of problems such as low transmittance and low refractive index temperature stability, which will affect the imaging quality. To solve these problems, the secondary imaging panoramic ring optical system with two mirrors as the head unit is adopted in this paper to create the conditions for the introduction of the aperture of the field of view for the suppression of stray light. Based on the aberration theory, the initial structural design method of the panoramic ring optical system with two-reflection lens unit is discussed. The Q-type aspherical surface profile description is introduced as an important variable in head element optimization. A panoramic band infrared optical system was designed with field of view (50°~70°) ×360°, focal length 7.5 mm, F-number 1.5 and working spectrum 8 ~10 μm. The design results show that the modulation transfer function of the system is better than 0.5 at the Nyquist frequency (20 lp line pair/mm), and the imaging quality is good. The stray light outside the designed field of view can be effectively suppressed to meet the needs of practical applications.