An extremely severe EF4 tornado struck Funing County, Jiangsu Province on 23 June 2016. The tornado killed 99 people, injured 846 others, and damaged many buildings. This paper focuses on the synoptic environment and mesoscale characteristics of the tornado by using all kinds of observation data. The tornado occurred in the most sensitive area and season with highest tornado occurrence frequency in East China. The synoptic environment for the tornado was the typical rainstorm circulation in Meiyu season. The tornadoproduced mesoscale convective system occurred in the south side of the surface warm front where the highlevel jet coupled with the lowlevel jet. The strong deeplevel dynamical forcing characteristics are significant accompanied by highlevel jet, and the thermaldynamic unstable condition is moderately strong. The tornadoproduced mesoscale convective system was a discrete cell with elliptically shaped region of reflectivity which is the most favorable convective mode for significant tornado in the United States continent. The structure of cell is the same as the typical super cell with bow echo， severe mesocyclone and tornado vortex signature (TVS). Funing tornado was in the top of the bow echo and occurred during the period when the height of the mesocyclones was lower than 1 km.