Concerning the increasingly severe deterioration of air quality in Jiangsu Province, we designed a regional air quality multi mode forecast and early warning system which consisted of a data center, a computation center, an analysis and display center, and a forecast center. We employed some key techniques, including air quality forecast from ensemble multi mode system, warehousing OLAP, data mining technique and intelligent association technique. The establishment of the system will provide scientific and timely technical support for the government and relevant units which are able to make regional linked air pollution prevention, control, and emergency measures.