Abstract: Since the enforcement of China 1 emission standards in 2000, vehicle emission regulations are getting more and more stringent to enhance the pollution control. In-use compliance (IUC) is an important part of the vehicle emission control, and it will be enforced for the heavy-duty vehicles with the China 4 emission standards. Studies on the IUC of heavy-duty vehicles have just begun in China; and there are shortcomings in the operation and effectiveness of engine dynamometer test. The research and enforcement progress of the on-board testing methods for IUC of heavy-duty vehicles in European Union and the United States was introduced, as well as some preliminary studies carried out in China, which could be reference for the enhancement of China’s IUC program of heavy-duty vehicles. In addition, the portable emissions measurement system (PEMS) for on-board test was introduced briefly.