Based on analysis of circulation background, influencing system and the characteristics of physical quantity fields on each layer, the diagnostic analysiswas performed on theweatherprocess of the snowstorm happened inTangshanRegion during3 to4March in 2007 by usingMICAPS data and NCEP 1°×1°6-hour interval reanalyzed data. The results are as follows: the deepening upper trough, the vortex at700 hPa layer and the intensive cold airweremain influencing systems that cause the snowstorm weatherprocess;the divergence athigh level and convergence at low leve,l the enhanced positive vortex, the strong ascendingmotion and thewarm air forced to liftby cold airwere the importantdynamicmechanism of thisweatherevent; the vapour transportcame from the deflection east airstream at the low layer; and theQ-vector convergence at700 hPa correlated to the area of snowstorm’s occurrence, which can be used as an indicator in forecasting snowstorm weather.