Abstract: Using hourly precipitation observation data of 4890 meteorological observation stations in Sichuan, 24 cases of nocturnal rainstorm processes occurring in northeastern Sichuan basin during the period from 2015 to 2019 were screened out. Based on the classification and synthesis analysis of nighttime rainstorms according to the influence system, the near-surface flow field was decomposed into circumfluence and creeping flow by using the equations of bypass flow and creeping flow, and the influence of topography on airflow and nocturnal rainstorms in the northeast part of the basin were explored. The study shows that the nocturnal rainstorm in northeastern Sichuan basin can be divided into southwest vortex type and southerly wind type. The southwest low vortex and low trough are strengthened at night in each types, causing a significant strengthening of the southerly flow and vertical motion at night. A large amount of water vapor enters northeastern basin from Guizhou and Chongqing at 850hPa and forms a strong water vapor convergence center at midnight. The transport and convergence of water vapor in the southwest vortex type are stronger than those in the southerly wind type. The southwest vortex type is more unstable in the late midnight in the northeast of the basin, and the vertical motion of the southerly wind type is stronger in the windward slope of Daba Mountain in the late night. The creeping and circumfluence movements in the topographic uplift area of northeastern basin also have the characteristics of nighttime strengthening. The creeping and circumfluence movements of southwest vortex type are stronger than that of the southerly wind type. The vertical movement forced by the creeping flow can well reflect the vertical upward movement formed by the southerly airflow at the terrain uplift, while the flow around the terrain is conducive to the generation and strengthening of the local vortex. The spatial distribution of the two types of rainstorms corresponds well to the large value area of positive vorticity at night.