Based on the routine upper level and surface meteorological observation data, the temperature of black body(TBB) data from FY-2G satellite and ECWMF dataset with a spatial resolution of 0.125°×0.125°, a regional snowstorm occurring in Shaanxi Province on 3 January 2018 was analyzed. The results show that the regional snowstorm occurred under the background of 500 hPa deep trough caused by cut-off low, 700 hPa southwest jet and 850 hPa easterly air flow. The efficient water vapor from Bay of Bengal and East China Sea was transited by strong low level southwest jet and easterly air flow, respectively, which was one of the main causes of the snowstorm. The intrusion of cold flow in middle level was the main trigger mechanism. Strong upward motion caused by the upper level divergence and low level convergence and the development and maintenance of positive vorticity in middle and low level were the dynamic mechanism of the snowstorm. The meso-β scale convective cloud cluster with minimum TBB  of -50 ℃ developed in the process of eastward moving of convective cloud cluster with the length of 1100 km, the width of 40 km and TBB equal to or less than -40 ℃, which caused the short-time heavy snowfall with precipitation intensity more than or equal to 2 mm·h-1. As an elevated convection case, the updraft increased due to the slantwise convection triggered by conditional symmetric instability. The echo band was parallel to 0-6 km vertical wind shear, and the snow area was consistent with the moving direction of the flow.