Abstract: In order to expose precipitation structures in both horizontal and vertical,and responses of microwave brightness temperatures to precipitation distribution and intensity,in this study,we studied two meascale heavy rain systems happening near Wuhan on July 20,1998 and the southern part of Anhui on June 9,1999 by using standard data of 2A25 derived from TRMM PR and 1B11 from TMI.Results show that connective rains contribute much more rainfall to the total than stratiform rains although the former occupies less area than the latter inside the two heavy rain systems,respectively,due to the stronger rainfall rate of connective rains.Results also show the two heavy rain systems are consisted of several heavy convective rain blocks and rain bands in horizontal inside the two systems.Generally,the horizontal scale of rain blocks is from 10 km to 50 km,and rain bands have near a hundred kilometer in length with width from 10 km to 20 km inside the two mid-range scale heavy rain systems.Between the heavy rain blocks (bands),there exist weak rainfall regions or even no rain regions.Usually,strong connective precipitating clouds are surrounded by stratiform precipitating clouds.In vertical,the rain top of heavy connective rains can reach to 15 km from the surface.Inside these heavy connective rains,rainrate is distributed heterogeneously in vertical and horizontal.Meanwhile stratiform rains have a clear brightness band near freezing layer.Above the layer,there exist multi-layer clouds.Below the layer,the rainfall rate is almost constant,which means no collision process during rain droplets drop off from the layer.However,for connective rains,there exists a clear collision process for rain droplet below the freezing layer.But the depth of the collision process for connective rains varies possibly due to connective precipitating clouds are in their different stages.Below the layer of collision process,there may be a layer of droplet evaporation process or big droplet breaking process for connective rains.The differences between connective and stratiform rains are also indicated in their precipitation profiles and the normalized counter rainrate altitude diagram (NCRAD).The NCRAD indicates that a wider distribution of rainfall rates for connective rains comparing with a narrow one for stratiform rains.Analysis on microwave brightness temperatures of TMI channels exposed bad responses of low frequency channels at 10.7 GHz,19.4 GHz,22 GHz and 37 GHz to rainfall over land.However,there are good responses of the polarization corrected temperature at 85.5 GHz and the vertical polarization differences between 19.4 GHz and 37 GHz,19.7 GHz and 85.5 GHz,37 GHz and 85.5 GHz to surface rainfall over land.Results illustrate that rainfall region is covered by values of less than 270 K at the polarization corrected temperature at 85.5 GHz,and values of greater than zero at the vertical polarization differences between 19.4 GHz and 37 GHz,19.7 GHz and 85.5 GHz,37 GHz and 85.5 GHz.