A high-performance liquid chromatographic（HPLC） method for the determination of relative substances in thioctic acid tablets was developed.The separation of analyte was performed on a Waters XBridge column（5 μm，150 mm×4.6 mm） with phosphate buffer（pH value was adjusted to 2.5 with phosphoric acid）-acetonitrile-methanol（50∶45∶5） as mobile phase，at a flow rate of 1.0 mL/min and an injection volume of 20 μL.The photo-diode array detector（PDA） was set at 220 nm，with full scan range of 200-400 nm.The column temperature was ambient.Under the above chromatographic conditions，the calibration curve was linear（r=0.999 9） in thioctic acid concentration range of 0.4-20.0 mg/L.The limit of detection（LOD） for thioctic acid was 0.2 mg/L and the limit of quantitation（LOQ） was 0.6 mg/L.The relative standard deviation（RSD，n=12） was 3.4%,and the average spiked recovery was 100.9% with RSD of 2.0%.The proposed method could be applied in the determination of relative substances in thioctic acid tablets with the advantages of simplicity，rapidity，accuracy，good selectivity and high sensitivity.