In this paper, atmospheric turbidity and extinction property in the Xizang Plateau during the warm season are discussed. It is found that the index of aerosol particle a is 1.9, and that the aerosol’s radius on the Xizang Plateau is twice as many as in the plain of Bast China. Turbidity coefficient ?changes obviously with the elevation and season, and the same trend for transparency of atmosphere is revealed also. It shows that the atmospheric turbidity in the Xizang Plateau is determined by vapour and areosol, and Rayleigh scattering- and others are not the main factors.