A new method for the determination of rebamipide in human heparin sodium plasma by LC-MS was established and its methodology was validated. In this method, protein precipitation method was used to pretreat the samples and the rebamipide-d4 isotope of rebamipide was used as the internal standard. In the multi reaction monitoring mode, the electrospray ion source was used as the ionization technolog and LC-MS was used for detection and analysis. The liquid chromatographic conditions were: 00B-4605-AN (Kinetex® XB-C18 100A 50mm × 2.1mm, 5μm); mobile phase A: 0.1% FA and 1 mM NH4FA aqueous solution, mobile phase B: 0.1% FA and 1mM NH4FA 90% ACN solution, flow rate: 0.300mL/min, injection volume: 10uL, column temperature: 30oC, collection time: 3 min, injector temperature control: 5oC. The retention time of rebamipide and rebamipide-d4 were 1.32min and 1.31min, respectively. The lower limit of quantification was 1ng/mL and the calibration map of rebamipide in the concentration range of 1 to 800ng/mL was linear (R2 >0.990, n=11). The CV% values of the inter and intra batch precision of the method were both less than 15.0%. This method has been successfully applied to pharmacokinetic studies to evaluate the main pharmacokinetic parameters of rebamipide.