Abstract: In this paper the relationship between clear-sky planetary and surface albedos is derived by the physical model of atmosphere-earth system. It is suggested that the planetary albedo is a linear function if the single ground reflection is considered,and is two power parabola function if the ground multireflection is considered,By use of the data of the TIPMEX-86 (Tibetan Plateau Meteorological Experiment-1986) and GAC (Global Area Coverage) data,the experiment was carried out in order to test the relationship, The result shows that two functions fit well into the relationship betweea clear-skp planetary and surface albedo over the Qinghai-Xizang plateau, but physical aneaning of two power function is more clear-cut.