Infrared stealth technology plays a vital role in improving the survivability of future aircraft. The exhaust system is the main source of infrared radiation on the rear side of the aircraft, and stealth coating is an effective measure to reduce the infrared radiation on the solid wall of the nozzle. Mature commercial computational fluid dynamics software was used to obtain and analyze accurate data of the flow field to study the infrared radiation characteristics of the stealth coating on the turbofan engine nozzle. Furthermore, infrared simulation software based on the reverse Monte Carlo method, line-by-line calculation technique, and database technology for high-temperature gas parameters of a narrowband model were used to numerically simulate the exhaust system of a turbofan engine with infrared suppression coating. Assuming that the damage percentage of the external adjusting plate is constant, the findings reveal that the overall infrared radiation intensity exhibits a steadily increasing trend with the increase in the number of damaged adjusting plates. The maximum change in the infrared radiation intensity between eight damaged adjusting plates and one damaged adjusting plate was 11.67%. Thus, regular inspection and maintenance are required for the stealth coating on the external adjusting plate of the aero-engine tail nozzle to maintain stealth integrity.