Since the existence of buried targets influences the thermal physical properties of the surrounding area, causing the temperature differences over time in the regional surface, which reflected in the infrared image is the gray value changes over time. To solve the problem, we research on the mathematical model of temperature change of the region containing buried targets, and reveal the relationship between the regional temperature changes and thermal physical properties and buried position of the buried targets. We use real multi-temporal and multi-spectral infrared images to get the temperature distribution of the region surface which compared with the solution of the mathematical model. By continuously changing the value of the thermal model parameters, we can get a solution which consistent with the temperature distribution obtained by the real temporal infrared images, and then we complete the detection of subsurface targets.