Using satellite cloud pictures and data from the intensive and conventional observation, the reason of the heavy rainfall event on 16-17 July 2004 over Shall river area is studied. The results show that the event is directly affected by the formation and evolution of southwest vortex and MCC cloud cluster which locate in the intersection region of the upper-level jet and the low-level jet. In addition, a thought of how to use the mesoscale convergence center, TBB of convective cloud and the radar echo for rainfall rate to predict the mesoscale rain cluster is presented.