Ground-based simultaneous observations of sun direct and scattering radiation were carried out in Dunhuang for nearly 2 years.Aerosol optical depth, Angstrom wavelength exponent and size distribution were obtained from solar extinction and sky radiation. Water vapor content was obtained from sun direct radiation measurement at 940 nm. Relationship between aerosol properties and water vapor was discussed. Results showed that distinct seasonality of aerosol optical depth and Angstrom wavelength exponent was corresponding to seasonal variation of dust activity. Aerosol relative size distribution kept stable and volume concentration change was the reason resulting in variation of aerosol optical depth. Water vapor had minor effects on aerosol optical and physical properties.