OBJECTIVE： To establish the method for the determination of tigecycline （TGC） in human plasma. METHODS： After precipitated by acetonitrile， the plasma sample was determined by LC-MS/MS. Using d9-TGC as internal standard， Kromasil C18 column was used with mobile phase consisted of water （containing 0.05％ TFA）-acetonitrile （gradient elution） at flow rate of 0.6 ml/min， column temperature of 40 ℃. The ion transitions were performed under ESI positive MRM model at m/z 586.3→513.2 and m/z 595.3→514.3 for TGC and internal standard， respectively. RESULTS： The linear range of TGC was 25-2 000 ng/ml （r＝0.999 8）， and lowest quantification limit was 25 ng/ml； intra-day and inter-day RSD was 3.15％-7.23％， and relative error was     －4.53％-10.48％. Plasma sample kept stable after 3 times of freezing and thawing cycle， at room temperature for 24 h， in automatic sample injector for 24 h and freezing for 42 d （RSD＜15％）. Plasma concentration of TGC was 0-438.0 ng/ml in one patient with pan-drug resistant bacteria infection（0-12 h after administration）. CONCLUSIONS： The developed method is accurate， sensitive and specific， and can be used for plasma concentration determination of TGC and pharmacokinetic study.