The hardware-in loop simulation technology was employed to design the indoor hardware-in loop simulation system for infrared sensor of terminal sensitivity projectile. This system employs the Multi-Gen Creator to build the scene model and the attacked target three-dimensional geometrical model as well as employs the Multi-Gen Vega to produce the digital scene of detection field for terminal sensing projectile. Meanwhile, the detection system of terminal sensitivity projectile-infrared sensor was served as the substance and introduced into the simulation system to participate in the test and consist of the closed loop with other software systems and optical system complete the real-time simulation function of terminal sensitivity projectile. The simulation result indicates that the infrared sensor can completely identify the target and is provided with such advantages as low false detection ratio and low omission ratio.