Abstract: Based on the 30-years’ rainfall data of a repre-sentative meterological station and the 25-years’rainfall data of 43 hydrometric stations in the Taihu Lake reglon,the new algorIthn of rainfall erosivity factor(R-value)was improved which showed a coincidence with the classical algorithm at the rdte of 9O% of the temporal and spacial variation characteris-tics of R-value in the Taihu Lake region or Changjiang biver basin,and the R-value(25-years’)distribution map in the whole region was compiled as well.Applicatlon of R-value to soil and water conservation,tillage system transformation,flood prevention and disaster mitigation and,in particular,the fundamental reason for the big flood disaster in 1991 in Taihu Lake region were discussed.Owing to the larger R-value in this region, the soil conservation should not be ignored.Adopting soil conservation measures in the mountainous ar-eas,especially for the slope land,constitutes a basically per-manent and effective method for flood prevention and disaster mitigation. 

Key words: rainfall erosivity factor, soil loss monitor-ing, flood prevention and disaster mitigation