This study was conducted to examine the impact of vehicular traffic emissions on the seasonal trends of polycyclic aromatic hydrocarbons (PAHs) concentration in particulate matter in Beijing. The PM₁₀ and PM_2.5 samples were collected at an urban site near the Third Ring Road in Beijing, China, from July 2009 to March 2010. Individual PAH concentrations at urban traffic site ranged from n.d. (below the detection limit, 0.2 ng/m³) to 558.49 ng/m³ of benzo(b)fluoranthene in PM₁₀ samples and from n.d. to 177.93 ng/m³ also for benzo(b)fluoranthene in PM_2.5 samples. Seasonal variations of PAHs compounds indicated that PAHs concentration in autumn and winter was higher than those in spring and summer. Results of PCA give four and five significant factors, which could explain 83.1% of the variation for PM_2.5 and 85.3% of the variation for PM₁₀, respectively.