Abstract: This paper makes a research on non-methane organic gas(NMOG)emission properties under different working conditions using ultra-low light-duty gasoline vehicles constant volume sampling system and carbonyl group sampling,analysises equipments in 4WD chassis dynamometer and for the light-duty gasoline vehicles,and tests conditions including NEDC,WLTP and FTP75 three basic conditions.According to the study,the results showed that the pollutants relationship of quantity under three kinds of work condition is NEDCWLTPFTP75,and the NMOG emissions quality size relations is NEDCFTP75WLTP.In either case,the mass ratio of NMOG emissions in the first stage to the total working condition is greater than the other stages of the working condition.Under three conditions,the light-duty gasoline vehicles generate NMHC,formaldehyde,acetaldehyde,and acetone,are the four main pollutants accounting for a large propotion of NMOG emissions。