Abstract: The octanol-water partition coefficient,log P and biological activity of sulfadrugs were both correlated with HPLC parameter,log k'(capacity factor).By comparing these two kinds of relationships,it was found that the log P in Hansch'sequation might be substituted by log k'in the correlation of chemical structure with the minimum inhibitory concentration of the tested sulfa drugs against E.coli in vitro, and good correlations were obtained.