Organic compounds containing a variety of functional groups have been analyzed using aerosol time-of-flight laser mass spectrometry designed in our lab. Positive laser des-orption/ionization time-of-flight mass spectra (LDI-TOFMS) and it's formation mechanism have been acquired for phenol, aniline, 1, 3-dichlorobenzene, nitrobenzene. The results show that the single aerosol particles of aromatic compounds can easily lose a electron to form a molecular ion spectrum , and its functional group is liable to disintegrate, too. This can offer some basic information of some aromatic group aerosol particles and the interpretation and analysis method of atmospheric aerosol.