As the leading air control weapon in modern warfare, stealth aircraft has excellent ability of aerodynamic performance and extremely high battlefield concealment. Nevertheless, the aerodynamic thermal effect of aircraft skin and the unshielded part of exhaust plume still have a considerable infrared radiation level with the stealth aircraft moving at high speed, which provides an important basis for the infrared detection of the stealth aircraft. In this paper, the infrared radiation characteristics of stealth aircraft are studied for the photoelectric countermeasure technology in modern complex battlefield. Based on the in-house developed physically-reasonable photoelectric simulation system PRISM, the typical stealth aircraft geometric modeling, the skin temperature field calculation, and the exhaust plume physical field calculation are performed to obtain the zero line-of-sight radiation characteristics of the target. Combined with analysis of the atmospheric radiance transfer effect, the infrared radiation characteristics of the target at the detection distance of 20 km are calculated. The calculation results show that: 1) Using different infrared detection bands, the minimum values of the forward and backward radiation intensities of the target are located at the detection azimuth angles of 0° and 180°, respectively; 2) At the non-afterburning flight state, the target radiation intensity obtained by long-wave 8~12 μm detection is higher than that of mid-wave detection; at the detection azimuth angle of 0°, the long-wave infrared radiation intensity is approximately 140 W/Sr higher than that of mid-wave; 3) At the afterburning flight state, while detecting from the tail direction, the target radiation intensity obtained by mid-wave 3～5 μm detection is significantly higher than that of long-wave detection; at the detection azimuth angle of 0°, the long-wave infrared radiation intensity is approximately 400 W/Sr higher than that of mid-wave; 4) The aerodynamic heating effect on the skin is much more significant at the afterburning flight state; at the detection azimuth angle of 0°, the long-wave infrared radiation intensity is approximately 330 W/Sr higher than that of the non-afterburning state. The simulation results show that using the detection wavelength of 3～5 μm in the mid-wave infrared and 8～12 μm in the long-wave infrared, the PRISM system has good infrared imaging simulation capability for the stealth aircraft target under different flight states, which supports the infrared detection and photoelectric countermeasure research of the fifth-generation stealth aircraft.