Because the diesel engine has the advantages of high thermal efficiency, high power, low fuel consumption, so it is widely used in the field of agriculture, industry, national defence construction. In recent years, with the awareness of environmental protection, the world standard for exhaust emissions from diesel engine becomes more and more strict. Through scientific research, CO and HC in diesel emissions than gasoline engines much less, NOx emissions and gasoline engine similar to, but more exhaust particles, and the diesel engine combustion mechanism. This paper discusses the main measures to clean diesel particulate emissions, engine cleaning technology, external purification technology, as well as the present situation of diesel engine emission and control technology and its development trend.