Abstract: General observations and NCEP reanalysis data were used to comparatively analyse the synoptic evolution，water vapor and thermal conditions of the two snowfall processes between the first and middle period of february at Zhangjiajie．The result showed that southwest jet provided adequate water vapor for snowfall．The location and strength of southwest jet had close contact with the area and intensity of snowfall．Front lifting were the important dynamic and thermodynamic conditions to produce snowfall．There was a good correspondence among inversion temper layer，thickness of wet layer and the category and intensity of snowfall．