Abstract: Based on the conventional meteorological observation data,NCEP reanalysis data（1°×1°）,microwave radiometer data and the HYSPLIT model,the characteristics of water vapor transport during a heavy rain in the warm zone of Jizhong Plain on July 5,2021 was comparatively analyzed.The results showed that before the onset of precipitation in this process,the specific humidity of 925 hPa and 850 hPa were above 12 g/kg by applying the analysis of the HYSPLIT model simulation,which were the main water vapor contributors in the rainstorm area,and the main water vapor channels were the southwest route,the contribution rate of water vapor accounted for 57.57% and 63.64% respectively.Under the guidance of the southeast turning southwest airflow,the air masses which were originated from the Yellow Sea or passed through the Yellow Sea,Bohai Sea,etc.,brought abundant water vapor to the lower layers of the rainstorm area.At the same time,the air masses originating from the middle and high levels of the Eurasian continent,brought dry air to 500 hPa over the rainstorm area,which constituted an unstable stratification of upper dry and lower wet along with the movement of the longwave troughs and ridges in the westerly zone.Before the start of precipitation,under the action of the corresponding guiding airflow at 925 hPa and850 hPa,water vapor were continuously transported to the central Jizhong Plain,so that the excellent water vapor conditions were mainly concentrated in the lower atmosphere,which was consistent with the simulation results of the HYSPLIT model.The water vapor characteristics which were analyzed by microwave radiometer,showed that the water vapor content at altitudes below 700 hPa increased significantly before the rainfall started,and the maximum water vapor density reached 14 g/m~3.Three different data were analyzed to get similar conclusions,but the application of the two high-temporal-spatial-resolution data of the HYSPLIT mode and microwave radiometer can analyze the water vapor characteristics in a more timely and detailed manner,and provide accurate forecast and early warning of the rainstorm falling area and intensity in warm regions.