Modeling and simulation have wide applications in the performance design, test evaluation, and combat simulation of IR detection systems. To meet the need for the performance modeling of IR detection systems in complex combat scenes, the effects of the detector array structure, sampling efficiency, image blur, and other factors on detection were analyzed based on the traditional geometric model, and the effects of clutter and human interference on detection in complex scenarios was analyzed. All these factors were introduced into the performance modeling of the IR detection system, and an IR detection system model that can be applied to complex scenes was established. Simulation examples show that the model can realistically simulate the performance characteristics of IR detection systems in complex combat scenes and has important application value in IR detection system design, performance evaluation, and combat test simulation.