Polycyclic aromatic hydrocarbons（PAHs） in atmospheric fine particles in different seasons and different function areas of Guiyang city were sampled and observed, 16 priority PAHs were analyzed by using HPLC equipped with UVD and FLD dual detector. The results showed that PAHs of PM_2.5 were found in Main Urban Area of Guiyang, the total annual concentration ranged from 4.44 ng/m³ to 114 ng/m³, of which the lowest concentration appeared in summer while the highest concentration in winter, and the average concentration was 24.96 ng/m³ in five sampling sites. In different seasons, the concentration of PAHs of the atmospheric PM_2.5 in different functional areas was varied, and the change trend was different. PAHs were dominated by 4-6 ring monomers, which accounted for more than 68% of the total concentration. Sources apportionment results indicated that the source of PAHs in PM_2.5 in Guiyang showed obvious seasonal characteristics, the main source was fossil oil combustion in spring, summer and autumn, there were also a small amount of biofuel combustion, and the main source in winter was coal and fossil oil combustion. The toxicity evaluation results of PAHs in fine particulate matter showed that PAHs in the atmosphere of Guiyang had lower health risks in spring, summer and autumn but higher health risks in winter.The concentrations of benzo［a］pyrene which is strong carcinogenic were below the GB 3095—2012 limits(2.50 ng/m³). However, except for the background sampling sites, the other sampling sites all exceeded the standard limits in winter, and the maximum value exceeded the standard ratio of 3.80 times.