Objective:To study the antimicrobial effect and screen antimicrobial effective parts of the tubers and fibrous roots of Bletilla striata.Method: Filter paper method and photoelectric turbidimetry method were carried out to evaluate the antibacterial effect of the extracts of the tubers and fibrous roots of B.striata.The system solvent extraction method was adopt to further location of the active sub-fractions.Finally

HPLC method was applied to compare the chemical difference between tubers and fibrous root extract of B.striata.Result: The aqueous extract of tubers and fibrous roots of B.striata had no inhibitory effect while the 95% ethanol extracts of both tubers and fibrous root showed antibacterial effect;sub-fraction analysis manifested that the chloroform layer

ethyl acetate and n-butanol layer were the active part of the tubers and fibrous

which the ethyl acetate layer of the fibrous roots with the strongest inhibitory activity.HPLC revealed that the chemical composition of 95% ethanol extraction of both fibrous roots and tubers of B.striata were similar

while the former had remarkable amounts of content in several components.Conclusion: The antibacterial active components were mainly deposit in the hydrophobic 95% ethanol extract for both fibrous roots and tubers of B.striata

and they were similar in chemical composition

while the former showed higher amount of chemical components and better antibacterial activity

which implied the fibrous roots of B.striata with potential value.