To meet the demand of reconnaissance in modern military equipment, a novel conformal infrared optical system was presented. Two axial translation phase plate were used to correct the dynamic aberrations which were caused by the conformal structure.For the designed optical system, the working band was 3.7μm~4.8μm, the focal length was 40mm, the ratio of length to aperture was 1.0, the instantaneous angle was 2°, and the scan angle is ±15°, respectively. The results show that the modulation transfer function of each scan fields of view is greater than 0.6 with the nyquist frequency of 17lp/mm, and the optical transfer function is comparable to the diffraction limit. The spot of several scan fields is less than 30μm and falls within the area of one pixel. The designed optical system with well optical performance can be a suitable candidate for the application of the mid-infrared refrigerated focal plane array detector with the pixel size of 30μm×30μm. This research is potentially helpful for the further development and application of new imaging optical equipment in the military field.