The characteristics of water vapor conditions of stratiform cloud and its potential for rainfall enhancement in the autumn 2002 in Henan Province have been investigated by means of data from meteorological observation, from upper air soundings at 3 h intervals, and from Ground Based Dual Wavelength Microwave Radiometer (GBDWMR) system and meteorological satellite and combined with the results of MM5V3. It is shown from the analysis of those data that the main positions of potential are located at the 700－300 hPa level at 07:00, 13:00, 16:00 BT moment. As the result of model simulation, it is beneficial for the formation of rain in which the content of supercooled liquid water is abundant while the number concentration of ice crystal is little.