Abstract: Aiming to the portable mass spectra existing overlapped peaks that impacted the identification of the analyte, the method of overlapped peak resolution based on wavelet transform was researched. The wavelet function selecting, confirming the wavelet decomposition level, selecting the detail portion of wavelet coefficients and the magnification of the details were studied when this method was used to process the overlapped peaks. It used the simulative overlapped large-large peaks，large-small peaks and the measured DMMP overlapped peaks in the experiment. The results show that using the presented method to distinguish the overlapped peaks, the resolution of large-large peak is improved by 128.57%, the large-small peak is 52.0%, and the measured DMMP data is improved by 33.75% at least, compared with the resolution of original data.