Based on the realtime meteorological observation and the Mesoscale Numerical M odel (MM5V3), and supported by on the GIS application System, in pivot serving a rea of the Yellow River Basin (from Tuoketuo County to Wanjiazhai Reservoir),th e realtime rainfall of Yellow River Basin and the reservoir was monitored and t he warning index was automatically calculated. The arearainfall forecast of the Yellow River Basin (from Tuoketuo county to Wanjiazhai Reservoir) was output . The system was used in the oprational application, and provided the service f or Tianqiao hydropower station, Wanjiazhai Reservoir,the enterprises and some de partments of the government through the information issuing platform.