Using the routine meteorological data and AMDAR aircraft meteorological data, the objective diagnostic analysis of two severe aircraft icing events happened on 5 and 23 January 2012 in Guiyang Airport is made. The results show that these two severe aircraft icing events were caused by a stationary front; an inversion layer maintained a long time; the inversion layer top and inversion thickness were essentially the same; temperature inversion strength was enhanced; saturated cold clouds maintained and cold cloud water content continued to increase; the low level inversion layer and saturated wet layer supplied favorable temperature and moisture conditions for severe icing. AMDAR data is a strong complement to radiosonde data, which can reveal the subtle changes of atmospheric stratification over time and provide references for icing warning and forecast service.