Based on the data of aerological and surface meteorological observation for many years，the trend of water vapor content and its transport over Lanzhou city were analyzed deeply. Results are as follows：（1）The water vapor content and its transport are relatively more in summer than that in winter，and the water vapor content increases from Feb to Jul，decreases from Sep to Jan，and keeps invariable in Jul and Aug；nearly 97% water vapor content concentrates below the height of 400 hPa；（2）The trend of water vapor content distinctly corresponds to the change of precipitation，rainy days and temperature，but also there are some differences；（ 3 ）Over Lanzhou city，the large center of water vapor transport is near the height of 500 hPa，the maximum diurnal variation of water vapor is at the layer of 700 ～ 600 hPa in winter，and these are obviously different from those over the east of China.

Abstract:Using the data of Dopplor radar and reanalysis data of NECP/NCAR, the rainstorm process which occurred on August 27,
28 in 2003 in Gansu province was analyzed in this paper. The results show that the reason of veer degree of zero speed line differing
from one side to the other side of the station was the big scale confluence adding on the warm advection, the structure offered advan-
tageous vertical vapor transportation and confluence rising for producing and maintaining strong precipitation; upwind section and
middle-small scale confluence ( divergence) were in close connection with strong precipitation and that is an important index on pre-
cipitation prediction; the region and amount of precipitation have connection with the amount of vapor flux transportation and the de-
gree of vapor confluence.