Abstract: A ground-based sky radiometer was used to measure direct and diffuse solar irradiances, as well as aureole radiances, from October 2003 to August 2004 over Yinchuan, China. The aerosol optical depth (AOD), Angstrom exponent (α), volume size distributions, refraction index and single scattering albedo of aerosols were simultaneously retrieved using the SKYRAD model. The diurnal variability of AOD in Yinchuan was significant, with its change amplitude of about 31%, 33%, 24% and 38% in spring, summer, autumn and winter, respectively，and it mainly had two patterns. The AOD varied seasonally with a vernal maximum and a winter minimum, while the variation in αwas opposite to AOD, with a vernal minimum and a winter maximum. This is associated with the activities of sandstorms in northern China. The aerosol volume size distributions presented a bimodal structure, i.e., an accumulation mode with a radius of about 0.15 μm and a coarse mode with a radius of about 7 μm. The latter had a concentration far greater than the former. The real part of the refraction index rose dramatically in spring, and exhibited a low sensitivity to wavelength; but its imaginary part decreased noticeably in spring, showing an even lower sensitivity to wavelength, and the variation was more complicated. The aerosol single scattering albedo in spring was much higher than that in other seasons, and increased dramatically with increasing wavelength. In other seasons, the magnitude of the aerosol single scattering albedo showed random small changes with wavelength.