The characteristics of air quality in Jinan are studied on the basis of the daily air pollution index (API) from 2001 to 2005. The average API was 96.2 for the period, and the number of days with good air quality accounted for 64.7%. Annual average numbers of days with slight pollution and middle pollution were 124.8 and 20 in the 5 year period, respectively. As a whole, the city is relatively polluted. The relationship of API and wind speed in Jinan has a Ushaped curve, with higher APIsat the wind speeds being less than 2 m/s and higher than 6 m/s and with lower APIs at the wind speeds in the range of 2 to 6 m/s. The moderate or above pollution was caused mainly by weather: sand storms or blowing sands followed by cyclones and cold fronts, and smog or fog followed by breeze. Clear air days were mainly accompanied with the weathers patterns affected by the rearward of cold fronts or cold highs.