Abstract: In order to study the characteristics of rainstorm in Inner Mongolia and to guard against the impact on agriculture from flood disasters caused by rainstorm, based on the NCEP/NCAR reanalysis and the conventional observation data, the heavy rain had been analyzed in eastern Inner Mongolia during 24-28 July 2011. Results showed that: (1) north China trough was stopped by high pressure dam in the Okhotsk sea was the large scale circulation background of the heavy rain process. With the subtropical westerly frontal zone of the upper-level and the low-level jet stream coupling together. (2) Coupling effect that the upper-level jet stream of 200 hPa lever and the low- level south wind jet stream of 850 hPa lever continuing and stable coordinating provided dynamic condition and stratification conditions for the persistent heavy rain, the coupling effect was important for the heavy rain.