Using LASGREM model，a numerical experiment of the heavy rainfall in the north and central Henan Province on 5 to 6 July of 2000 is made. The result shows that the humidity at 850hPa is the most important factor effecting rainfall，and the Taihang Mountain also affects the rainfall area and the position of the most intensity of the rainfall as well. Besides，wind has some effects on the distribution of rainfall area.