During summer the southern part of China to the south of the Huaihe R iver is vulnerable to the threat of the heavy rainfall causing flood damages. Th e rainstorms usually appear on a stationary front which is situated along the ri ver basins. There is a monsoon surge to the south of the stationary front bringi ng moisture into the rainstorms. The relation between the monsoon surge and the heavy rainfall causing flood damages in southern China is studied . It is found that the intraseasonal variability of the general oscillation from the equatorial Indian Ocean named the MaddenJulian Oscillation (MJO) is most p rominent in Asian and Australian monsoon sectors. When MJO propagates to the Sou th China Sea sectors, the west winds (monsoon) at 850hPa will strengthen and the sector convection will be enhanced. At the same time, there is a monsoon surge in the southern part of China. When the monsoon surge meets with cold air from northern China, there will be severe rainstorms along the stationary front.