For the rarely researches that the atmospheric environment effects of Southwest Vortex(SWV), routinely observed meteorological data, air pollution monitoring data, atmospheric sounding data and Climate Forecast System Version 2 (CFSv2) products have been used to counted the number of SWV in winter and spring 2014 -2016 and the synchronous air quality grade with diagnostic and statistical methods in this study.It is found that SWVs developed in spring and winter are mostly dry low vortices due to the lack of water vapor.This type of SWV rarely induces precipitation and can easily cause air pollution weather in the Sichuan Basin.Based on those results, a dry and a wet SWV in Sichuan Basin in 2015 were selected for comparative study.The analysis of a severe air pollution over the Sichuan Basin from 29 December 2015 to 3 January 2016 suggests that a dry SWV was generated over Sichuan Basin on 30 December with weak intensity and small thickness.The foehn effect arising from the weak descending motion at the rear of dry SWV caused an intensive untouched?ground low?level inversion over Chengdu, generated a ‘pot cover’ effect that suppressed the diffusion of air pollutants, brought about an quite small maximum mixing depth and surface wind speed which presented an obvious stagnate synoptic status, gave rise to the concentrations of PM₁₀ and PM_2.5 of representative cities in basin were 398 and 268 μg·m^-3, respectively, which were the peak values during this heavy air pollution process.In contrast, the study found that, during August 16 -17, 2015, the strong upward movement and heavy precipitation resulted from the wet SWV produced the extremely favorable effects of atmospheric diffusion and wet deposition, rapidly and effectively reduced the concentration of pollutants, which was opposed to the environmental effect of the dry SWV that aggravating atmospheric pollution.