Abstract: Hybrid refractive-diffractive design offers a new approach for athermalization design in wide temperature range. In this paper, working wavelength is in 3-5 m. For cool 320240 infrared detector, pixel size 30 m30 m, this system can realize 400 mm and 800 mm dual filed-of-view and the F-number of 2/4 respectively. Two systems both can obtain the cold shield efficiency of 100% though controlling machine structure. A diffractive surface was introduced in the shared part of two different focal length position. It achieve the athermal design using only one diffractive surface. The evolution of the system was given in the temperature range -40-60℃. The results show that at the spatial frequency of 18 lp/mm the MTF approach to the diffractive limitation.