Influenced by the interaction effect between southwest warm air and weak cold air,intense and long duration rainstorm happened in Xinjiang River watershed of Poyang lake drainage net on July 16耀20,2010. Then the flood in 50 years occurred in Xinjiang River and the super historical flood occurred in Baita River, a tributary of Xinjiang River. This paper makes a comprehensive analysis of the 2010 flood from the comparison of rainstorm and flood between 2010 and 1998. It is helpful to urther understand the meteorological and hydrological characteristics of the river basin, to improve the accuracy of hydrological forecasting, and there is also important reference value to the future flood control work.