The invention provides a method for detecting oxidized glutathione impurities in a glutathione-rich yeast extract. According to the method, oxidized glutathione is subjected to qualitative and quantitative detection by virtue of a high performance liquid chromatograph through an external standard method; the retaining time of the oxidized glutathione on a chromatographic column is regulated and controlled by virtue of a methanol/water binary mobile phase, so that the detection of the content of the oxidized glutathione in the yeast is accurate and credible; the mass concentration of the oxidized glutathione presents a good linear relation at 0.25mg/mL-4.00mg/mL; and the minimum detection concentration of the oxidized glutathione impurities in the extract is 7 micrograms per milliliter. The method has the beneficial effects that the operation is simple and efficient, the oxidized glutathione impurities can be conveniently detected, and good production quality guarantee is provided for the control of yeast products rich in reduced glutathione.