A quaternary ammonium compound (HSDA – HTC) was applied to cotton fabrics to enhance their antimicrobial property. Two kinds of finishing methods were discussed and compared, which were dipping method and dip-roll-dry method. The influence factors which affect the quantity of quaternary ammonium group and antimicrobial quality of fabrics were studied and discussed. The result of experiments showed that dip-roll-dry method is better than dipping method. The optimum finishing condition is to dip cotton fabric in 2 g/L HSDA – HTC at the temperature of 80 ℃, to roll it with pick-up at 100%, and to dry it at 110 ℃ for 5 minutes. The test of fabrics’ antimicrobial property indicated that the cotton fabric finished under the optimiun conditions showed highly antibacterial effect.