At two monitoring points established in a certain typical hypo-artery road in road net,Shanghai,measurements of the emission factors of pollutions from motor vehicles were carried out and the concentration of the pollutants,traffic activity and meteorological data were gained.The source intensities and the average motor vehicle emission factors of pollutions were calculated by using reversed extrusion of atmospheric dispersion model according to different meteoric conditions at monitoring points.Based on that,combined emission factors of 8 types of city vehicles were calculated by use of linear regression.