In this paper, the sensitivity of Escherichia coli to surfactin and fengycin was observed, and the optimization of the antimicrobial activity of surfactin and fengycin to E. coli in milk by a response surface methodology was studied. Results showed that E. coli had high sensitivity to these antibiotics, whose minimal inhibitory concentrations were 15.625 mu g center dot mL(-1) and 31.25 mu g center dot mL(-1), respectively. The optimization result indicated that E. coli could be sterilized by 5 orders of magnitude when the temperature was 5.5 degrees C, the action time was 15.8 h, and the concentration (surfactin/fengycin weight ratio 1:1) was 14.63 mu g center dot mL(-1).