摘要：As one of the most important environmental problems, air quality has always been highly valued by the government and society. The analysis of air quality in key cities can provide a basis for how to evaluate air quality and how to classify air quality levels and from what aspects it is helpful to improve air quality. The air quality of 51 key cities of environmental protection in China is analyzed and evaluated by selecting 7 indicators of air quality as the original variables. Cluster analysis was used to classify the key environmental protection cities preliminarily, and it was found that the air quality of the cities with fast development level was relatively poor, and the air quality of coastal cities was similar. It is found that the air quality of northern cities is generally worse than that of southern cities, and that of inland cities is generally worse than that of coastal cities. At last, according to the research results, some reasonable conclusions and suggestions are given.
