By taking the main pollutants in the air in Chongqing, Beijing, Tianjin and Shanghai during 2001-2011 as basic data, API air pollution index model is set up, the sub-indicator of each pollutant is calculated, the weight of each pollutant is obtained by using the sub-indicator of this model and via analytic hierarchy process, and the suggestions and measures for improving air environment quality in the four municipalities are advanced according to the status quo of the pollution in the four municipalities and the situation of the main pollutants in the chief pollution sources as well as based on “the Twelfth Five-year Development Plan” in the each place.