Two precipitation processes, occured on 25 May and 12 May 1987 respectively in Wuhan area, were analysed quantitatively by means of variation and average adjustment technique using digital radar echo and rainfall data collected with auto-raingagues.The results have shown that the average adjustment technique, would reduce errors of radar measurement, but the peak values of precipitation were smoothed out. The variation technique is used to fit the distribution measured by radar into that by .auto-raingagues but keep the precipitation detected by radar in. its original pattern. The relative error is less than 10%.