Abstract : To investigate the formation mechanism and topographical influence of autumn torrential rains in Guizhou Province under the influence of easterly airflow , we analyze the causes and water vapor characteristics of the heavy rainfall event in Guizhou Province in October 18 - 19 , 2024 , by utilizing surface automatic weather station observations , ERA5 reanalysis data , and the HYSPLIT model , and incorporating topographical features . The results are that : (1) This process was an autumn cold front-type rainstorm triggered by a low-level easterly flow . The heavy rainfall lasted for a long time and the rainfall areas had significant topographic features . (2) Low- level easterly flow activities , which triggered severe convection several times forming rainfall stacks , was the main cause of the heavy rainfall . The triggering mechanisms were the 850 hPa mesoscale shear line , convergence zones , and interactions between easterly winds and terrain . (3) The water vapor contributing layer in the rainstorm area was mainly concentrated near 850 hPa , with the southern boundary as the main water vapor input boundary during the first stage of rainfall . Then , in the second stage , the low-level easterly airflow was enhanced to open up the east-branch water vapor transport channel , with the southern and eastern boundaries as the main water vapor input boundaries . (4) The mid-level water vapor in the storm area originated from the Bay of Bengal , the Arabian Sea area and the Indian Peninsula , transported by the southwest and westward paths , while the low-level water vapor was from the South China Sea and the Yellow Sea , transported by the southward and eastward paths . (5 ) The obstruction of the terrain that is high in the west and low in the east led to no water vapor outflow from the lower western boundary of the storm area. Thus , water vapor accumulated on the windward slopes of the mountain ranges . Under the combined influence of the 850 hPa shear line , convergence zones and the terrain uplift of the Wumeng Mountains and the Leigong Mountains , the vertical transport was formed providing sufficient water vapor conditions for the continuous development of the rainstorms . The topography of Guizhou Province exerted a significant impact on the formation of easterly rainstorm in terms of both dynamic factors and water vapor. This is a valuable insight for future research on the mechanisms of such weather phenomena.