The mesoscale numerical model (MM5V3) was used on the personal computer in Shenyang Regional Meteorological Center. There are some differences between MM5V3 and MM5V2 when MM5V3 was compiled by Fortran 90 in its pre process and post process. The longitudinal and latitudinal grid data set of the initial field and the boundary was created by T106L19 and sounding data set. The outputs of prediction were joined with plotting systems of Vis5d and Grads. The results of MM5V3 are better than those of MM5V2 which had been used in 2000 flood season, but not all.