Abstract: The characteristics of atmospheric boundary layer structure and turbulent flux transport in a cold weather process and their relations with PM₁₀ pollution in Lanzhou on April 19, 2007 were analyzed based on the data of gradient measurements of meteorological tower, turbulent flux measurements and PM10 concentration observed at Semiarid Climate and Environment Observatory of Lanzhou University. The main results revealed that there was a temperature inverse layer before the occurrence of the cold weather process. As the cold front passed by, the temperature inverse layer was broken, and a mixing layer developed quickly. The vertical gradients of air temperature and humidity in the lower boundary layer was sharply decreased, and that of wind speed was significantly increased. The PM₁₀ concentration was increased at first and then decreased. The vertical turbulent transport was very strong when the cold front passed by. The vertical momentum fluxes of meridional and latitudinal velocity were transported downward, and the vertical momentum flux of the meridional velocity was high. The turbulent momentum downward transported, especially the downward momentum flux of meridional velocity, was the main factor which caused the dust blowing and the PM₁₀ pollution at the beginning of the cold weather process.