The rainfall estimate is conducted for the southwestern Guizhou Province (eight counties and one city) by means of the Doppler radar data (volume scan) and automatic weather station data in 2004, considering the geographical and climatic features and the distance away from the radar. The least square method is used to determine the relationship between radar echo intensity and precipitation. The statistical test is carried out by the data from January to July 2005 and the analysis of the errors is made from several aspects. The results are satisfactory and provide useful references for rainfall estimate.