Abstract: The daily characteristics and differences of basic physical quantities are comparatively analyzed in the background of Southwest Vortex and sunny days,based on the intensive sounding data in 2017 at Jiulong station,a main resource region of Southwest Vortex.The results are as follows:In the Southwest Vortex background,the boundary layer height is much lower,but in sunny days,atmosphere turbulence in the boundary layer acts actively and the boundary layer height can reach above 3000m.In the Southwest Vortex background,warm and wet air is dominant at night,air pressure is obviously low,and wind speed in the upper layer is big.While in sunny days,air is much dry,diurnal range of temperature is obvious,air pressure is high,and turbulence is mixing well in the daytime.These differences are much more remarkable near to the ground layer,and gradually decrease along the the height increasing.