Abstract: From the serological data of 1955-1961 in West China, the water cycle in the basin of the Up-Yangtze river in summer is investigated for each year, and the mean of six years is obtained.The water vapour transfer is closely related to the circulation pattern over this area in summer. The inflow of water vapour from the south is on the average over 85 per cent of the total inflow, and the inflow from the west is about 10 per cent. About 98 per cent of the total outflow passes through the eastern and northern boundaries, so that there is a high negative correlation between the outflow through the east and north. The intensity of inflow from the south does not change significantly, while the outflow through the eastern and northern boundary is quite different, from year to year.When the inflow of water vapour is large (or small), the outflow from this area is also large (or small), hence the net inflow or runoff of the basin are not determined solely by the inflow of water vapour.In this region the coefficient of water cycle K (K=1.094) and the intensity of the water cycle are larger than in other regions of the world. The ratio of evapotranspiration to precipitation is relatively small and the maximum layer of water vapour transfer is situated between 850 and 700 mb. It is found that the orographic condition is an important factor for these characteristics of the water cycle in this region. We conclude that the possibility of the increase of the precipitation by increasing the internal evapotranspiration in this region is larger than in plain areas.