By using the data of radar and satellite, lightning positioning a nd NCEP data, the mesoscale characteristics of the excessive storm occurring in the western region along Huaihe in Anhui on July 8th，2007 were analyzed. The re sults show that the big convective echo band producing the excessive storm was c onsistent with the convergence area at 925hPa. The convective cell moved in the same direction as echo band, but the mesoscale rainstorms pro pagated backwards. It moved in the oppositional direction with the single cell w hich made the big echo relatively stable in a specific area and caused the exces sive storm. The maximum hourly precipitation almost appeared when intense convec tion and convective echo merging. Furthermore by analyzing the twodimension al wind field retrieved of single Doppler radar, the cyclonic shear maintaining at low and middle level was the important condition which caused and maintained the severe rainfall.