Abstract: In this paper, first, the facts of the temporal and space distributions for climatic cloud cover and the vertical profiles of relative humidity over Asia were analysed. Then, the comparison tests of six sets of diagnostic schemes for cloud amount were carried out for four cases in 1979 covering Winter, Spring, and Summer, utilizing a six-level limited area model with complex terrain and model physics processes, the FGGE data of 1979,and the observed cloud cover data combined by ourselves. Finally, a sensitive test of effect of cloud amount on short range weather prediction was conducted.The results show: 1) there are obvious temporal-and space-variations of cloud cover over Asia. The characteristics of cloud cover and relative humidity over Asia are something different from those over Atlantic. 2) Among above six schemes both the modified ECMWF and modified climate cloud ones taken cloud characteristics of Asia into account have the best performance for the diagnoses of high-and lower-cloud areas and cover, especially for high-cloud. 3) The changes in claud amount have no significant influence on the short range prediction over large area, but may have a certain,influences on the prediction over a particular local region, i.e., with the increase in cloud amount, the temperature in mid-and lower-troposphere gets warmer, the precipnation light.