The dust case was analyzed by using aerosol extinction coefficient sequence chart retrieved by lidar observation data and meteorological observation data. The key factor of these two dust cases occurred was the dust transferred from North China, and the key reason of those two dust cases maintain so long was exogenous input and the vertical wind. The atmospheric profile affected the intensity of dust case. The dust case was holding when the temperature inversion occurred at the ground. The solar radiation affected the height of boundary layer. The main particulate matter is big size particle in the first dust case, and the aerosol scattering coefficient was higher than the aerosol absorption coefficient. The proportion of PM2.5 rose in the reflux dust case, and the aerosol scattering coefficient corresponded to the aerosol absorption coefficient.