Abstract: Cloud is a comprehensive reflection of atmospheric vertical motion and the wet conditions, and changes in cloud amount also represent the climate change in another aspect.And any changes of cloud parameters in climate models may has a significant impact on the global climate.The main study results on cloud in recent decades are summarized, which include the temporal and spatial distribution of cloudiness, the relationship between cloud and precipitation, the difference among the several cloud datasets.On the basis of above, it is suggested that the character of cloud and its variations in the Southwest China, Characterized by maximum cloud amount and the thickest cloud area within inland China, should be much studied.