Based on wire icing observations at Huashan Meteorological Station from 1980 to 2007 and convention observational data at 95 meteorological stations in Shaanxi Province, the correlations of wire icing thickness with convention meteorological data were analyzed. On this basis, we calculated the standard wire icing thickness at 10 m height above the ground level over the years, estimated the extreme wire icing thickness with a recurrence period of 30 years and of 50 years by means of the method of extreme value type I distribution. According to the design experience of the Shaanxi Electric Power Design Institution, the present situation in Shaanxi Province Electric Power System and historical electrical network icing accident investigations, an elementary grid icing division is made. The results are presented as follows，the biggest icing thickness has positive relationships with annual rime days and annual glaze days. Six different regions of wire icing were separated across the province, and wire icing maps of 1 to 500000 scales with a recurrence period of 30 years and of 50 years were drawn. This result has been used as important basis for wire icing thickness design in the Shaanxi Province electric power construction.