Abstract: Using of the eight times per day TBB dataset observed by GMS/JAPAN during the year from 1981 to 1994 and the two times per day OLR dataset observed by NOAA Satellite/USA, the diurnal and seasonal variation of convective cloud system over Tibet and its zonal movement are studied. The results show that there is an obvious diurnal variation of convective cloud over Qinghai-Xizang Plateau during summer. The convection arrives its strongest hour in 15-17UTC and its weakest hour in 0-5UTC. During the period from the middle ten days of July to the first ten days of August after the onset of summer monsoon, there are three low value centers of TBB which are located over the central part (30-320°N.900°E).the eastern part (300°N. 970°E) and the western part (300°N, 85-870°E) of Tibet.The monthly climate height of cloud top can arrive to 9.6km and the ten days average height in some region can arrive to 13km. The convective cloud begins to develop in the eastern part, then moves westwards and arrives to the west part in the middle and last ten days of July. During that time, the deep convective cloud can temporally develop in the western part of Tibet. Besides. the feature of convective cloud is also analyzed for the summer.1994.