Abstract: The influence of different polarity solvents on the antimicrobial effect of Yucca gloriosa L. extraction was studied, and the optimum extraction conditions were confirmed with L₉(3⁴) orthogonal experiment. Results show that the antimicrobial effects of Yucca gloriosa L. extraction with different solvents are significantly different. All the solvents themselves and petroleum ether extraction, trichloromethane extraction and ethyl acetate extraction produce little effects on fungus, though the antimicrobial effects of ethanol extraction, butyl alcohol extraction and water extraction on Penicillium dititatum, Botrytis allii Munn and Botrytis cinerea Pers isolated from garlic stem are significant, among which the antimicrobial effect of ethanol extraction is the best, while no effect of them on Penicillium italicum and no significant effect on Botrytis cinerea Pers isolated from grape, respectively. The optimum extraction conditions are as follows: ethanol concentration is 45%, the ratio of solid to liquid is 1∶20(g/mL), extracting temperature is 70℃, extracting time is 3 h.