Abstract: The hypersonic cruise missile undergoes aerodynamic heating, and the scarfskin has a high temperature, generating strong infrared radiation. In order to detect and warn hypersonic cruise missile effectively, it is important to study the spatial distribution characteristics of infrared radiation of hypersonic cruise missile. Firstly, taking X-51A hypersonic cruise missile as the research object, the geometric model of hypersonic cruise missile was established by using software SpaceClaim. Secondly, based on the basic conservation law of hydrodynamics, Fluent software was used to numerically simulate the hypersonic cruise missile's outflow field, and the distribution data such as the missile scarfskin temperature and the pressure around the flow field were obtained. Finally, Monte Carlo method was used to simulate the process of radiation transfer, and the space distribution of middle and far infrared intensity of X-51A aircraft under typical flight conditions was obtained. The results show that the temperature at the head and front section of the inlet of hypersonic cruise missiles is relatively high. At flight speeds of 5 Ma and 6 Ma, the maximum temperature of the skin reaches 1177.304 K and 1654.08 K, respectively. As the flight speed increases, the proportion of infrared radiation intensity in the skin increases. In the direction of α=78.75°, the infrared radiation intensity of the skin reaches its strongest. For 5 Ma, the infrared radiation intensity in the middle and far reaches 1.66×10⁴ W/sr and 6.0×10³ W/sr, respectively. However, in the head-on or tail direction, the infrared radiation intensity is weaker.