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Objective: To investigate the mechanism by which total alkaloids of Sophora alopecuroides (TASA) and matrine (MT) impair biofilm to increase the susceptibility of Staphylococcus epidermidis (S.epidermidis)to ciprofloxacin.Methods: The minimum biofilm inhibitory concentration (mBIC) was determined using a 2-fold dilution method.Structure of biofilm of S.epidermidis was examined by Confocal Laser Scanning Microscope (CLSM).The cellular reactive oxygen species (ROS) was determined using a DCFH-DA assay.The key factors related to the regulation of ROS were accessed using respective kits.Results: TASA and MT were more beneficial to impair biofilm of S.epidermidis than ciprofloxacin (CIP)(P ＜ 0.05).TASA and MT were not easily developed resistance to biofilm-producing S.epidermidis.The mBIC of CIP decreased by 2-6-fold following the treatment of sub-biofilm inhibitory concentration (sub-BIC) TASA and MT,whereas the mBIC of CIP increased by 2-fold following a treatment of sub-BIC CIP from the first to sixth generations.TASA and MT can improve the production of ROS in biofilm-producing S.epidermidis.The ROS content was decreased 23％-33％ following the treatment of submBIC CIP,whereas ROS content increased 7％-24％ following treatment with TASA + CIP and MT + CIP combination from the first to sixth generations.Nitric oxide (NO) as a ROS,which was consistent with the previously confirmed relationship between ROS and drug resistance.Related regulatory factors-superoxide dismutase (SOD) and glutathione peroxidase (GSH) could synergistically maintain the redox balance in vivo.Conclusion: TASA and MT enhanced reactive oxygen species to restore the susceptibility of S.epidermidis to ciprofloxacin.