Abstract: Based on the observation of the automatic ground stations and NCEP/NCAR reanalysis data,the regional heavy rain in Sichuan basin from August 8 to 9 2014 was analyzed,and the rainstorm process was simulated by WRF V4.0 numerical model.In the case that the simulation results are in good agreement with the actual situation,the influence of parallel ridge valley in east Sichuan on the rainstorm area and intensity is analyzed by the terrain sensitivity tests.The study shows that the rainstorm is caused by the stable maintenance of the high trough in the background of the subtropical high in the western Pacific cut off by the tropical cyclone.The control test of WRF V4.0 model can reproduce the rainstorm process well.The parallel ridge valley in east Sichuan has a great influence on the area and intensity of precipitation.The elevated parallel ridge valley in east Sichuan makes the rain belts in the central to northern parts of the basin move westward,and the precipitation in the western part of the basin increases,while that in the northern part of the basin decreases.Further study shows that the elevated parallel ridge valley in east Sichuan changes the 700hPa circulation situation and 850hPa water vapor convergence distribution in Sichuan basin through topographic convergence and forced uplift,which affects the precipitation area and intensity,and has less influence on the 850hPa circulation situation.