Abstract: To study the antibacterial activity of Dehydroepiandrosterone(DHEA)in sweet potato residue,the antibacterial activity of DHEA was tested with Kluyveromyces marxianus,Saccharomyces cerevisiae,L. rhamnosus,E.coli,Bacillus subtilis,Bacillus anthraci,Salmonella,Staphylococcus aureus. Bacillus subtilis,Salmonella,Staphylococcus aureus and Bifidobacterium as the indicator bacteria. The antimicrobial activity of dehydroepiandrosterone was studied by turbidimetry,minimal inhibitory concentration(MIC),minimum bactericidal concentration(MBC),growth curve and scanning electron microscopy. The results showed that the bacteriostatic effect of DHEA on the tested bacteria was as follows:Kluyveromyces marxianus>Escherichia coli>Staphylococcus aureus>Bacillus anthracis>Salmonella>Bacillus subtilis>Saccharomyces cerevisiae>Lactobacillus rhamnosus. The minimum bactericidal concentration were as follows:Kluyveromyces marxianus 5.67 mg/mL,Escherichia coli 9.82 mg/mL,Staphylococcus aureus 13.52 mg/mL,Bacillus anthracis 16.46 mg/mL,Salmonella 17.68 mg/mL,Bacillus subtilis 17.87 mg/mL,Saccharomyces cerevisiae 20.82 mg/mL,Lactobacillus rhamnosus had no significant inhibitory effect. DHEA shortened the growth cycle of the test bacteria and reduced the cell concentration. Scanning electron microscopy showed that the morphology of the cells was changed after DHEA treatment,the cell wall ruptured and the cell contents were partially eluted. The research showed that DHEA in sweet potato residue had inhibitory effects on most bacteria.