[Objective] To prepare flavonoids and polyphenols with different polarity from roots and flowers of Caragana microphylla Lam., and to test their antimicrobial activities in vitro. [Method] Roots and flowers were subjected to crude extraction and liquid-liquid partitioning after ultrasound-assisted crude extraction. The antimicrobial activity of resultant extracts and fractions were determined, and the correlations between their antimicrobial activity and total flavonoid and total polyphenol contents were analyzed. [Result] The fractions and crude extract show inhibitory effect on Bacillus subtilis and Fusarium spp., but did not show substantial inhibitory effect against Staphylococcu saureus and Escheichia coli. Dichloromethane fraction of flower crude extract exhibited the highest inhibitory activity against B. subtilis and Fusarium spp., with titers of 176.78 IU/mg and 243.97 IU/mg, respectively. Correlation analyses suggested that flavonoids and polyphenols were compounds responsible for inhibitory effect of C. microphylla on B. subtilis and Fusarium spp. [Conclusion] Flavonoids and polyphenols from flowers and roots of C. microphylla may have various applications and great potential in development of plant-derived antimicrobial food additives, fresh fruit preservatives and medicines. [Objective] To prepare flavonoids and polyphenols with different polarity from roots and flowers of Caragana microphylla Lam., And to test their antimicrobial activities in vitro. [Method] Roots and flowers were subjected to crude extraction and liquid-liquid partitioning after ultrasound-assisted crude extraction. The antimicrobial activity of the results extracts and fractions were determined, and the correlations between their antimicrobial activity and total flavonoid and total polyphenol contents were analyzed. [Result] The fractions and crude extract show inhibitory effect on Bacillus subtilis and Fusarium spp., but did not show substantial inhibitory effect against Staphylococcu saureus and Escheichia coli. Dichloromethane fraction of flower crude extract exhibited the highest inhibitory activity against B. subtilis and Fusarium spp., with titers of 176.78 IU / mg and 243.97 IU / mg, respectively. Correlation Analyses suggested that flavonoids and polyphenols were compounds responsibl e for inhibitory effect of C. microphylla on B. subtilis and Fusarium spp. [Conclusion] Flavonoids and polyphenols from flowers and roots of C. microphylla may have various applications and great potential in development of plant-derived antimicrobial food additives, fresh fruit preservatives and medicines.