Abstract: Pollution property of PAHs in the particulates in the air and its affecting factors at the traffic crossing in Beijing were studied. Samples of TSP, PM₁₀ and PM_2.5 were collected at one of the major traffic crossings, Chongwenmen crossing, in June 2000. The mass concentration of PAHs in the particulates was measured. The flux of vehicles through the crossing during sampling was also investigated. Results showed that vehicle emission was the major source of PAHs in the particulates at the traffic crossing. PAHs were mainly in the particulates of small size. The mass concentration of PAHs went up with the increase of the flux of vehicles in the daytime. At night the mass concentration of PAHs was higher than that in the daytime. The identification of pollution sources showed that a small part of PAHs in the particulates at the traffic crossing came from the raised dust in the street beside the emission of the vehicles.