The wide snowstorm in the middle and south of north China on 10-11 November 2009 was analyzed using the NCEP reanalysis data and the general automatic meteorological observing stations data. The results indicate that: (1)The snowstorm occurred in the weather system of upper trough on 500 hPa, low vortex and shear line, and Hetao front occlusion on 700 hPa. (2)The snowstorm located in the right back of the entrance of polar front jet stream and the front left of the subtropical jet stream on 200 hPa, the front left of Southwest jet stream on 700 hPa, and the front right of the easterly jet stream on 925 hPa and 850 hPa. (3)The snowstorm was caused by the jet streams at different altitudes. The low-level jet was formed and developed under the coupling of upper-level jet. The easy-coupling area is where positive vorticity advection is increasing when the altitude increases, in the right of the entrance area of the upper-level jet or the left of the exit area of upper-level jet. (4)Southwest jet stream has provided adequate water vapor for the snowstorm and formed the high-humidity area, which made and maintained the convection instability layer in the snowstorm area. (5)Southwest jet stream and Northerly jet stream formed convergence zone over the snowstorm area, which set up the raising movement of the weather scale for the snowstorm. (6)The secondary circulation caused by the coupling of upper-level and low-level jet increased the raising movement, triggered the release of unstable energy, and increased the intensity and duration of the snowstorm. (7)Easterlies on 925 hPa formed dry and cold mattress in the boundary layer of the snowstorm area, which helped the southerly warm and humid air to climb and strengthen dynamic lifting effect.