Based on daily precipitation data, upper-air observation data and ERA5 hourly reanalysis data with 0.25°×0.25° resolution from 2010 to 2020, the rainstorms caused by the northwest vortex in Shaanxi are counted, and the characteristics of rainstorms caused by the northwest vortex with and without influence of typhoon are comparatively analyzed. The results show that the rainstorms caused by the northwest vortex in Shaanxi mostly occurred in July and August, and it occurred more in northern Shaanxi. The night rain characteristics of the rainstorms are obvious. The rainstorm intensity was stronger under influence of typhoon, and the falling area was to the north of two latitudes than that without influence of typhoon. The northwest vortex, which caused rainstorms in Shaanxi, was located at about 7-8 latitudes to the north of the ridge line of the western Pacific subtropical high. The northwest vortex had the dynamic characteristics of convergence at low level and divergence at high level. The upward motion of the northwest vortex was strengthened by the topographic forcing uplift, and the low-level water vapor transport and convergence provided favorable conditions for the occurrence of rainstorms caused by the northwest vortex. Under the influence of typhoon, the subtropical high was westward and northward, the water vapor and energy in the periphery of the typhoon were transported to the northwest vortex with the southwesterly low-level jet, the atmosphere at lower layer of the northwest vortex was convective instability, and the positive vorticity advection in front of the high trough and strong divergence on the right side of the high-level jet promoted the development and enhancement of the vortex, the strong updrafts on the south and east sides of the vortex triggered the release of unstable energy and formed strong frontogenesis in northern Shaanxi, the frontogenesis further enhanced the vertical movement on the south and east sides of the vortex, which caused heavy rainstorms on the south and east sides of the vortex. When there was no influence of typhoon, the subtropical high was eastward and southward, the southwest wind speed was smaller and the water vapor transport was weaker, the southwest wind in front of the plateau trough transported water vapor from the Bay of Bengal and the South China Sea to Shaanxi, the atmosphere at lower layer of the northwest vortex was stable, the strong updraft was located in the south of the vortex, the cold and warm air converged in central and southern Shaanxi, which resulted in scattered weak frontogenesis and caused rainstorms in the south of the vortex center.