Infrared stealth is increasingly important in modern war, for active infrared detection the stealth material should perform high absorption. An infrared absorber which consists of a metal ground plane, a dielectric slab and resistance patches is designed based on the resistance frequency selective surface (RFSS). The absorption of the absorber is investigated by the CST Microwave Studio and the simulation results show that the absorption of the absorber in a wavelength range of both 3–5 μm and 8–12 μm is greater than 90%.