To study the difference in acute toxicity in mice and the content of toxic and active components of Xanthii Fructus before and after stir-frying.Methods:In the acute toxicity experiment，mice were administered by gavage，and the median lethal dose(LD50) and the maximum tolerated dose(MTD) in mice were determined.The damage to the liver，kidney，and other organs of mice was observed by histopathological sections.The content of two water-soluble glycosides and four phenolic acids of crude and processed Xanthii Fructus was quantitatively determined by high-performance liquid chromatography(HPLC).Results:MTDs of water decoction and precipitate after alcohol precipitation of crude Xanthii Fructus and water decoction and precipitate after alcohol precipitation of processed Xanthii Fructus were 291.73，405.75，318.64，and 480.77 g/kg(calculated based on the crude drug)，respectively.The LD50 values of supernatant after alcohol precipitation of crude and processed Xanthii Fructus were 468.18 and 573.48 g/kg(calculated based on the crude drug)，respectively.Hyperemia of different degrees was observed in the pathological sections of the main organs of the dead mice，especially in the liver，lung，stomach，and small intestine.The content of carboxyatractyloside in the water decoction and supernatant after alcohol precipitation decreased after stir-frying(both P<0.01)，and the content of caffeic acid and isochlorogenic acid C increased(both P<0.01).Conclusion:After stir-frying，the toxicity of Xanthii Fructus was significantly reduced and the dissolution of active components increased.The supernatant after alcohol precipitation of water decoction was the main toxic part of Xanthii Fructus.