Objective: To study antimicrobial activity of aqueous extract of maize silk. Methods: Choose Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus, Bacillus coli and Candida albicans as detected germs. Using methods of agar plated diffusions and tube continuous dilution to detect antimicrobial activity and minimum inhibitory concentration of aqueous extract of maize silk. Results:(1) Aqueous extract of maize silk has antimicrobial activity against bacteria such as Staphylococcus aureus and Bacillus subtilis, and the diameter of bacteriostatic circle is 17 and 28 millimeter; Candida albicans is also inhibited by aqueous extract and its diameter of bacteriostatic circle is 24 millimeter.(2)The antimicrobial activity against Staphylococcus aureus and Bacillus subtilis is 500mg/ml and 62.5mg/ml.The minimum inhibitory concentration to Candida albicans is 125mg/ml.(3) aqueous extract of maize silk has no antimicrobial activity on Pseudomonas aeruginosa and Bacillus coli. Conclusion: Staphylococcus aureus, Bacillus subtilis and Candida albicans can be inhibited by aqueous extract of maize silk.