The tail flame of the missile has the characteristics of high temperature,high brightness and large area,and the tail flame contains a lot of water and carbon dioxide,so that the flame spectrum of the missile has a peak near the wavelengths of 2.7 μm and 4.3 μm.For the radiations at the two wavelengths,a spectral restoration algorithm was proposed.Based on the radiation intensities at other wavelengths except the two wavelengths,the radiation intensities at the two wavelengths are estimated.According to the single peak and the adjustable characteristic of the Gaussian function and the univariate function,the peaks at two wavelengths can be restored,thus,detection and recognition of the missile in the atmosphere can be achieved through the space-based infrared detectors,and the theoretical database was constructed.To make up for the disadvantages of long spectrum database update cycle and great data for the current missile tail flame,considering actual spectral resolution of the detector,a four-point linear decision algorithm was proposed,and the feasibility of a series of methods has been proved by simulation.