Abstract: Experiments and detections of rain enhancement over a long period show that water vapor condition is an important and basic requirement for weather modification. An initiative analysis for three torrential rain processes of Heilongjiang Province in July of 1995, based on the water vapor images of GMS-5 with 6.7 μm channel which were offered recently and combined with the conventional weather data and satellite cloud picture etc, was made. It is shown that the three processes corresponded with three different types, respectively. A synthetical study of the continuous torrential rain process with an obvious water vapor band during 25~30, July was made. The water vapor images provided a clear and object imagery for the water vapor transfer band in warm area during the developing stage of this typical cyclone, therefore, the data for width and length of water vapor transfer band were obtained and the structures of temperature and humidity were analysed. The precipitation efficiency in the warm front was also estimated. Furthermore, the cloud physical characteristics of the precipitation process and the conditions for rain enhancement were analysed. So, the possibility of application of water vapor images in weather modification would be provided