Abstract: This paper discussed and analyzedthe effect of dust storms on urban air quality in both sand source and affectedregions on the basis of statistical data of dust storm events from 2001 to 2006and the air pollution index (API) data. Furthermore, the aerosol optical depth and angstrom exponent change characteristics were studied in dust-sand weather and non-dust-sand weather in Lanzhou and Beijing from 2005 to 2007. The research results show that the frequency of dust storms reduced slowly in recent years (it reduced at first, and then increased a bit), and the dust storms aggravated the atmospheric pollution. The influence of the dust storms on the source regions surpassed half of the regional background pollution levels. The average API in springdust weather of Lanzhou, Yinchuan, Hohhot and Baotou increased 64%, 53%, 86% and 90%, respectively, while the API of Beijing, Tianjin, Taiyuan, Shijiazhuang, Shenyang, Jinan, Xi’an and Zhengzhou increased 85%, 62%, 49%, 57%, 29%, 41%, 27%and 45%, respectively. In addition, the aerosol optical depth increased and theangstrom exponent decreased obviously when dust storms occurred.