Abstract: The aerosol optical properties were compared between source region of sand dust and its downwind region in the East Asia using the observational data from the AERONET site during 2001 to 2011. The results show that the aerosol optical depth is significantly higher over source regions than over its downwind regions during sand dust, while the reverse is true for the Angstr?m exponent and it decreases to zero or even negative when the dust storm appears. The volume spectrum distribution of aerosol particle size is a double peaks shape except in the Dunhuang site. The concentrations of fine particles are extremely higher in Xianghe and Beijing than in the Northwest area, which is caused by the fine particles together with pollutant aerosols. The averages of aerosol single scattering albedo are 0.93, 0.93 and 0.94 from 440 nm to 1020 nm in China, Korea and Japan. Compared with that in the downwind regions, the real part of refractive index is higher and the imaginary part is lower in the source regions. In general, the average of asymmetry factors at the four wavelengths is 0.70 in the East Asia under sand dust weather condition.