Spectrum intercomparison search means calculating the similarity of question spectrum and standard spectrum in the database to find the same or similar spectrum as the question spectrum. To weaken the impact of irrelevant information on spectrum intercomparison search results and improve the search accuracy, the question spectrum noise is taken for example and the impact of spectrum noise on the calculated similarity results is analyzed; for the characteristics that when infrared spectrum is multi-scale decomposed, the useful information is mainly concentrated in the low-frequency part and the high-frequency part is mainly noise, the infrared spectrum intercomparison search method based on wavelet multi-scale decomposition is proposed; the impact of spectrum decomposition level on the calculated similarity results is analyzed; the entire waveform search method is used as reference method and the search program of both methods is designed with MATLAB 7.0 and the feasibility of infrared spectrum intercomparison search method based on wavelet multi-scale decomposition is confirmed by the experimental results.