Abstract: The rapid development of automotive industry and the extraordinary growth of the vehicle population had brought about serious pollution problems in China. Through timely introduction of stricter emission standards for motor vehicles, vehicle emissions has decreased remarkably in China. Since implementation of China I emission standards, the emissions from each new vehicle had been reduced by 57%-96%. This has resulted in the decrease of average emission factors for the overall in-use vehicles, the effective control of the total emissions from motor vehicles and the improvement of the air quality in cities. Through implementation of strict vehicle emission standards in continual phases, emissions shows a downward trend, and a positive outcome of the total emission reduction is achieved.