Abstract: Infrared scene project (IRSP) is a key technology for infrared imaging hardware in the loop (HWIL) simulation. Real-time quality is very important for IRSP system. A design of IRSP system was presented. The IRSP system was composed of infrared image generation subsystem and infrared scene transformation subsystem. The two subsystems were based on general GPU and resistor array device respectively. Reflective memory network was used for image data transfer and frame synchronization to meet the demand of image size and frame rate for HWIL simulation. The real-time quality was evaluated by testing IR image frame period. The result indicates that significant errors occur unpredictably under Windows system and the frame period is unstable. A new real-time design was introduced based on RTX extension, and the detailed scheme was presented. Test results of the real-time design indicate that the reason for significant frame period error is the unpredictable interrupt response delay under Windows system and the real-time design under RTX extension can ensure a stable frame rate of 200 Hz under the control of frame synchronization.