In this paper, the calculated method of atmospheric turbidity over the Qinghai-Xizang Plateau is obtained by comparison of various methods to calculate Å ngstrom atmospheric turbidity.The atmospheric-turbidity ciefficients at some stations over the Qinghai-Xizang Plateau from August 1982 to July 1983 are calculated by using the observational data of solar direct radiation.and their characteristics are analysed.In addition, the empiric formula to calculate atmospheric turbidity coefficients are fitted by means of surface conventional meteorological data, the characteristics of temporal and spatial variations are analysed over the Qinghai-Xizang Plateau in thie paper.