PART5, a vehicle particulate emission factor model developed by USEPA, was modified and then used to obtain the emission factors of exhaust PM10 and PM2.5 from on-road automobiles, trucks and motorcycles in Beijing. The total exhaust PM10 and PM2.5 emissions from motor vehicles in 1995 and 1998 were calculated separately. The contribution ratios of different types of vehicles to the total vehicular emissions, and the share of different exhaust particulate components including Pb, direct SO4(2-), soluble organic fraction (SOF) and remaining carbon portion (RCP), were also estimated. It was shown that the emission factors of exhaust PM10 and PM2.5 from gasoline motor vehicles, motorcycles and heavy-duty diesel vehicles in Beijing were 1.7-8.6 times, 2.1-3.5 times and 1.3-1.5 times, respectively, of the USA average emission levels during the same period. The total exhaust PM10 and PM2.5 from vehicles were 2445 tons and 1890 tons in 1995 in Beijing, and increased to 3359 tons and 2694 tons in 1998, which increase by 37.4% and 42.5%, respectively.