Abstract: Local generated mesoscale vortexes (LMVs) in the lower reaches of the Yangtze is one key factor to improve rainstorm forecast accuracy since they can efficiently trigger and organize mesoscale convective systems (MCSs). There are many case studies focusing on the MCSs caused by LMVs, but in order to improve operational weather forecast ability during Meiyu season, the study about LMVs activities, structures and formative environment are necessary. Based on conventional weather data, satellite cloud images and numerical weather predictive outputs during Meiyu season of 1998—2005, the activities and structures of LMVs related to rainstorms in the lower reaches of the Yangtze are statistically analyzed, including the vortex generation, movement, life cycle, spatial range and related convective activities etc. Large scale environments and physical conditions are also synthetically analyzed. The result shows that LMVs in the lower reaches of Yangtze mainly generated around the Dabie Mountain area in Anhui Province. Typically, their horizontal scale changes from 100 km to 400 km, and most of them vary from 200 km to 300 km. Their vertical developing height usually changes from 1000 hPa to 700 hPa. LMVs moves mainly in two directions, one is northeast to as far as the Yellow Sea through north of Shandong Province, ant the other is southeastward towards the East China Sea through south of Jiangsu Province or north of Zhejiang Province. The life cycle of LMVs is less than 48 hours and it has no clear relations with their spatial scales. About 70% LMVs trigger single MCS or series MCSs and can lead to rainstorms. Rainstorms mainly happen to the south or southeast of LMVs, where there are enough warm and moisture flow. LMVs generated at the bottom of upper level trough of 500 hPa are especially possible to cause rainstorms. Analysis of large scale environments and physical conditions show more than 90% of LMVs develops at the bottom or in front of upper level trough at 500 hPa. The positive vorticity advection in front of upper level trough is necessary to LMVs generation and development. While the other conditions such as low level and upper level jet, middle level turbulence, low level moisture transfer and topographic conditions are all important to LMVs generation and development. Further studies such as mechanisms about LMV generation, development and the mechanisms about LMV trigger and organize MCSs are necessary.