Daily Air Pollution Index (API) were used to analyze the annual, seasonal and monthly variations of air quality in Lanzhou, Northwest China during 2001-2007. Differences in air quality during heating and non-heating seasons were also discussed. Combined with the daily surface meteorological observations from Lanzhou meteorological station, one-way ANOVA and correlation analysis were used to identify meteorological factors that have significant impact on PM₁₀ concentration in different seasons.The main conclusions are as follows: (1) PM₁₀ is the main pollutant in Lanzhou, there are peaks in December and March or April; (2) Number of pollution days decreases during 2001-2007, which is consistent with the decreasing trend of annual emissions of anthropogenic dust emissions; (3) Comparing  to non-heating season, PM₁₀ concentration in heating season decreases more significantly from 2001 to 2007, and more and more pollution days occur in heating season;(4) The main meteorological factors affecting PM₁₀ concentration are different for different seasons. In general, the wind speed, temperature and relative humidity (or precipitation) are the main meteorological factors affecting PM₁₀ concentrations in Lanzhou.