Based on GPS (Global Positioning System) data observed at the intervals of half an hour during the period of the Huanan (South China) Torrential Rainfall Experiment from 5 May to 26 June 1998,analysis results reveal that the characteristics of moisture variation and moisture increasing manner of the total water content with in the local column air.It indicates that increasing and decreasing of the total water content within the column in of discontinuity evidently.This is directly associated with variation of general circulation and with outbreak of Huanan Torrential Rainfall.