An automatic analytical method by HPLC for vapor and particle polycyclic aromatic hydrocarbons(PAHs) in ambient air is proposed. The PAHs were sampled simutaneously by a little volume and low noise sampling pump and extracted by a mixture of dichloromethane and methyl cyanide, concentrated by nitrogen sweeping, injected automatically and detected by a fluorometric detector with programmed excitation and emmission wavelength pairs. The mobile phase is a linear gradient mixture of methanol and water. The relative standard deviations of the retention time and peak height were 0 05%～0 39% and 0 68%～1 29%, respectively at PAHs concentration levels of 14 14～2360 0 μg/L with the linearly regressive factors being over 0 999. The detection limits were 5 30 ng/L for fluorene and 291 30 ng/L for fluoranthene.
