The indoor and outdoor air pollutant concentrations beside two trunk roads in Shanghai were measured. The air pollutants measured contain TSP, PM10, CO, CO2, NO2, formaldehyde (HCHO), benzene,toluene and xylene. The indoor and outdoor air pollutants and the correlation between them were analyzed. The diurnal variation rules of indoor and outdoor concentrations were studied. It is shown that: the level of indoor pollution beside the trunk road lies on the flow rate and the type of vehicles.