In this paper, the methods are discussed to define tile death-fire and fire region caused by the coal spontaneous combustion in the North of China. According to the theory of reflectance spectra of burnt rocks, the death fire area is defined by means of the interpretation of the aerial photographs. On the basis of the law of heat radiation, The border of the fire region is defired by means of the infrared scanning images, and the small regions by the means of the infrared measuring technology on the ground. And obvious economic profits have been acquired.