This standard is formulated in a bid to implement laws and regulations including the Environmental Protection Law of the People’s Republic of China and the Law of the People's Republic of China on the Prevention and Control of Atmospheric Pollution, prevent environmental pollution of the emission of exhaust pollutants from diesel engines of non-road mobile machinery and improve ambient air quality. The standard stipulates the limits and measurement methods for exhaust pollutants from diesel engines of non-road mobile machinery for Phase III and puts forward the predictive requirements for Phase IV. The standard adopts and revises the technical content regarding diesel engines of non-road mobile machinery of the EU DIRECTIVE 97/68/EC (up to the amendment of 2004/26/EC) on the approximation of the laws of the Member States relating to measures against the emission of gaseous and particulate pollutants from internal combustion engines to be installed in non-road mobile machinery.