Abstract： Objective： To observe the effect of Siwu Tang with Paeoniae Radix Alba fumigated with sulfur on endogenous metabolites in urine of rats. Methods：A total of 80 SPF grade SD rats were divided into the blank group，the Siwu Tang group with Paeoniae Radix Alba not fumigated with sulfur，the Siwu tang group with Paeoniae Radix Alba fumigated with sulfur， and the Siwu Tang group with all four medicinals fumigated with sulfur，with 20 rats in each group，half male，half female. The Siwu Tang group with Paeoniae Radix Alba not fumigated with sulfur was given the extract of Siwu Tang with Paeoniae Radix Alba not fumigated with sulfur；the Siwu Tang group with Paeoniae Radix Alba fumigated with sulfur was given the extract of Siwu Tang with Paeoniae Radix Alba fumigated with sulfur；the Siwu Tang group with all four medicinals fumigated with sulfur was given Siwu Tang with all four medicinals fumigated with sulfur； the blank group was given the same amount of distilled water； all groups were given the administration at a dose of 34.15 g/kg(the amount of crude herbs)，once a day for 14 consecutive weeks. The urine of rats in the four groups at the 6th，8th，10th，12th and 14th weeks was collected and analyzed by chromatography and mass spectrometry； the collected data were subjected to multivariate statistics. Results：The urine samples of rats in the four groups were separated from the 6th week，the separation at the 8th and 10th weeks was the most obvious，and the position on the score map tended to be stable at the 12th and 14th weeks. According to the PCA score map and load map of the four groups in the positive and negative ion modes，13 endogenous metabolic markers were preliminarily identified，mainly participating in 15 metabolic pathways， of which four metabolic pathways had an impact value greater than 0.1， namely， phenylalanine， tyrosine and tryptophan biosynthesis pathway， dicarboxylic acid metabolism pathway， pentose and glucuronide metabolism pathway and tyrosine metabolism pathway. Conclusion： The nephrotoxicity caused by Siwu Tang with Paeoniae Radix Alba fumigated with sulfur may be caused by the effect on phenylalanine，tyrosine and tryptophan biosynthesis pathway，dicarboxylic acid metabolism pathway，pentose and glucuronate metabolism pathway and tyrosine metabolism pathway.