Based on the statistical characteristics of rainstorm location and trajectory of the cyclone in the Huaihe River Basin during Meiyu period,the schemes of WRF numerical simulation are designed and the purpose is to investigate the orographic forcing mechanism of terrain of Dabie Mountains on the shallow rainstorm cyclone.Results show that:1)In the three simulation experiments,the eastward speed of cyclone is the fastest in the experiment without terrain of Dabie Mountains,the slowest for the cyclone going around northern mountains,and the medium for the cyclone passing over mountains.Without terrain of Dabie Mountains,the trajectory of the cyclone is obviously in the south of the trajectory of cyclone going around northern mountains,showing that the cyclone has a feature of moving along lowland.With inverted terrain of Dabie Mountains,affected by the large-scale mountain,the cyclone is forced to go around northern mountains,with a more north trajectory than those of the cyclone passing over mountain and the cyclone in experiment without terrain of Dabie Mountains.2)The effect of mountain on cyclone intensity is that it can offset and reduce the intensity when the cyclone going around northern mountains with an anticyclonic trajectory.In the experiment without terrain of Dabie Mountains,the cyclone maintains its intensity by self-system and is stronger than the cyclone going around northern mountains.When the cyclone has passed over the ridge of mountain,it has a double intensity,because the cyclone experienced a potential vorticity conservation process in front of and behind the ridge.3)The forced ascending motion of mountain with a large gradient is larger than the systematic uplift of cyclone.The vertical upward velocity with both mountain forcing and cyclonic convergence can increase nearly one times.4)The enhancing of total vorticity behind the ridge of mountain mainly shows that the low-level vorticity advection,twisting and divergence terms have marked increase,and their increments can reach up to one times,but the changes of the terms are small in the middle level.5)The strong rainfall usually happens in the north part of cyclone where the south jet met the east flow of the cyclone,indicating that a warning area of strong rainfall locates in the north part of rainstorm cyclone in the Huaihe River Basin.6)By the topographic forcing on eastward trajectory of cyclone,the mountains can further influence the north-south location of rainstorm zone.