摘要：This paper analyzes the air quality monitoring data of Qingyang, Tianshui and Pingliang in northwestern China in 2015 by time series analysis. The research results are as follows: (1) the concentrations of PM2.5, PM10and SO2in the three cities began to decline in March, reached a minimum in September before rising gradually; (2) concentrations of PM2.5, PM10and SO2in the three cities were low in summer and autumn, but high in winter and spring; (3) the coefficient of correlation among PM2.5, PM10and SO2in the three cities was greater than 0.589, indicating a strong correlation.
