Using a 3D hailstorm cloud model of Institute of Atmospheric Physics of Chinese Academy of Science, some features of cumulus-rainstorm evolvement brought by cold vortex occurring in the northeast zone of China from July 11 to 15，2002 are simulated. It shows that there is a feature of meso-small scale cumulus complex brought by cold vortex. Cumulus originates from a warmer zone of low layer and gains to grow due to strong updraft. There is an accumulation zone of super-cooled rainwater in the cold-vortex cumulus. Amount of super-cooled rainwater is generally accumulated above the position of the maximum updraft and changes with time. Hail develops in this zone. In the simulating area, many of single cumulus is united and formed a cumulus ensemble. There is a similar shape between the simulated cumulus and radar echo.