To solve the shortcomings of surface contamination detection, a new method based on brightness temperature spectroscopy was presented. Firstly, an infrared remote sensing spectrometer with high sensitivity was employed to acquire contamination′s spectrum in non-contact way. Taking advantage of the infrared source and the background having the same highly emission characteristics as blackbody, contaminants spectral features in brightness temperature spectra directly could be extracted by applying Planck′s law. As this method does not require a previous measured background spectrum, it is very appropriate to be applied to "poisoned" accident sites. The principles of this method were discussed. Then this method and background subtraction method were employed to detect polydimethylsiloxane(PDMS), triethyl phosphate(TEP) on aluminum plate. The experiment results show that, the spectral features of contaminants extracted by brightness temperature spectroscopy are same as those acquired by background subtraction. It means that brightness temperature spectral features can be used to identify contaminants directly. Because there is no need to take background spectra before identification, this method could respond to chemical threats immediately and reliably, which make it a great application potential in surface contamination detection.