Aerosol particles can influence climate considerably and have adverse impact on human health. Organic aerosols, a major component of aerosol particles, are directly emitted and formed from reactions between volatile organic compounds and atmospheric oxidants. The complexity of organic aerosols has inspired a number of separating and detecting methods. One of them, HRMS makes it possible to unambiguously identify multiple components in complex compounds based on the accurate mass measurements. For mass spectrometry analysis, organic compounds in aerosol particles are extracted with solvents before analysis. However, depending on the solvent, the extracted compounds can be different and affect the result. In this study, PM2.5 sample collected in Daegu was extracted with Water, DCM3:ACN1 respectively and sequentially. The extracts were analyzed by using LC FT-ICR-MS. For (-) ESI analysis, the numbers of formula assigned were 3794,3784,5268 respectively and for APCI(-) 991,1178,1510. So, sequential extraction of Water and DCM3:ACN1 is more effective and more data can be obtained. This experiment is intended to assist the solvent selection step in the analysis of organic aerosol compounds.