With GMS-5 water vapour images the upper tropospheric moisture distribution over the Tibetan Plateau is analyzed. It is indicated that water vapour accumulation over the Tibetan Plateau is mainly in one of the following ways: (a) Climbing up through Yarlung Zangbo River and Brahmaputra River valley; (b) Acrossing Himalayas; (c) Drifted from upstream Pamir through Tarim Basin; (d) Local ascending motion. Mean moisture pattern reveals a moisture region in the southeast part and a dry region in the northwest part of the Plateau. The boundary between the two regions is along the mountain ranges in the middle of the Plateau. This boundary is the place where new systems is triggered, which may cause regional precipitation later in the eastern part of China in July and August of 1995. Of seven major regional precipitation events in Northern China, five events were related with system triggered in the Tibetan Plateau. It is also shown that water vapour images can reveal the genesis of systems over the Plateau which are favorable to the improvement of regional, precipitation forecast for the eastern part of China.