Because the rainstorm precipitation amounts in the 2003 and 2006 Meiyu seasons are concentrated in the Huaihe Valley and their total precipitation amounts are different, the article has conducted the thorough research in the frontal zone structure by using the average field method. The results can be drawn as follows. (1) There was a clear Meiyu front area while heavy rain occurred, and the rainstorm precipitation amount and the frontal zone intensity are proportional. （2） Rainstorm area was located at the frontal zone, i.e. in the north of the hot and humid areas in the middlelower troposphere, and also north of the lowaltitude jet stream. (3) The shear deformation field of frontogenesis function overlapped with the rainstorm location, and the positive frontogenesis function area was shaped as an erect column and overlapped with the densified area of south wind isotachs. (4) Zonal distribution of the frontogenesis function instructed the rainstorm coverage.