To clarify the distribution characteristics of vehicle emission pollutant concentration (PM2.5 and VOCS) on the flat slope of mountainous city, taking eight typical roads in Chongqing as the research objects. The concentration of air pollutants at different lateral distances on the road sides was collected. The continuous distribution characteristics of PM2.5 and VOCS on different lateral distances on the side of the flat slope were analyzed, and the effects of different time periods and different environments on the concentration of pollutants were analyzed. The main findings of this research include the following. The PM2.5 and VOCS concentrations vary from the lateral distance between the roadside, but they show different characteristics. Concentration of pollutants at rush hours is higher than that at normal hours. Overall, the PM2.5 concentration of the road segment is greater than the VOCS concentration, and the PM2.5 concentration distribution is more dispersed than the VOCS concentration distribution. PM2.5 is more sensitive to the environment, and VOCS is less sensitive to the environment.