Abstract: The blended chitosan with a deacetylation degree over 90%,a viscosity-average molecular weight from 4.5×10~5 to 5.0×10~5,amounted for 60% of the total weight,and a viscosity-average molecular weight from 1.0×10~5 to 1.5×10~5,accounted for 40% was used.An effective chitosan antimicrobial agent was made from amino-organic-silicon micro-emulsion,evenly blended with 5% chitosan dissolved in 6% citric acid solution.Results show that the cotton fabrics treated with this agent exhibit good antimicrobial properties against staphylococcus aureus and Escherichia coli after 30 laundering cycles.