In this study, heavy-duty diesel vehicles were tested on chassis dynamometer and 23 carbonyl compounds were measured in the exhaust. Main influencing factors for carbonyl emissions were vehicle type, average speed and emission standard. Carbonyls emission factor of heavy duty diesel vehicles was 97.2 mg/km, higher than that of light-duty diesel vehicles and gasoline-powered vehicles. National carbonyl emission of diesel vehicles in China was estimated to be 45.8 Gg. The ozone formation potential of carbonyls was 537 mgO3/km, accounting for half of total ozone formation potential from diesel vehicles exhaust. Carbonyls emission from diesel vehicles exhaust should be considered a stringent issue in ozone control.