Based on the data of planet ary albedo, out going long wave radiation(OLR) and total cloud cover provided by ERBE and ISCCP, the effect of the t otal cloud cover on the earth-atmosphere systemnet cloud radiation forcing (NCRF) over the Tibetan Plateau is investigated. So is the relationship between NCRF and clear net radiation. Results show that there is an obvious non-linear correlation between NCRF and the total cloud cover,especially in warm seasons. Also there exists a better curve correlation between NCRF and clear net radiation in the earth-atmosphere system in each month, and each curve has a value of clear net radiation, which varies seasonally with astronomical radiation, corresponding to the zero value of NCRF. The geographical distributions of NCRF are related to total cloud cover and the earth-atmosphere system clear net radiation over the plateau.