To achieve the classification and recognition of rocket engine targets, it becomes necessary to extract the correlation between engine thrust and the infrared radiation intensity of the rocket exhaust plume. The High-Nitrogen, High-Energy GAP/Cl20/Al (GCA) and High-Nitrogen, Smokeless GAP/ADN/DAAOF (GAD) propellants are taken as the research objects of this study. Three parameters affecting motor thrust are numerically designed including combustion chamber pressure, nozzle expansion ratio and propellant formulation. A full-link computational method consisting of the motor internal flow, reacting flow field and infrared radiation is used to predict plume infrared signatures. On basis of this method, the correlation between the in-band radiation in the 2.7 μm and 4.3 μm bands of the under-expanded plume and motor thrust is established. Results show that motor thrust is log-linearly correlated with the radiant intensity under the variations of combustion chamber pressure and nozzle expansion ratio. At the same thrust level, the radiant intensity of the exhaust plume of GAD propellant is about 3~5 times lower than that of GCA. The combustion chamber pressure and nozzle expansion ratio can also be the dominant factors for thrust. For two types of propellant motors with different ambient conditions, the thrust and plume infrared radiation intensity approximately follow a unified logarithmic distribution relationship. The change in propellant formulation causes a weaker degree of change in motor thrust. Under different ambient pressures, the plume radiation intensity distribution of both high nitrogen propellants exhibits “aggregation” as the motor thrust changes. The radiation intensity in the 4.3 μm band exhibits a layered distribution phenomenon with ambient pressure as a function.