To study the influence of antidepressant effects of Sini Powder, Tiansi Liquid, and Peiyuan Jieyu Decoction on corticosrone and tryptophan 2, 3-double enzyme (TDO) and key metabolism enzyme of the tryptophan-kynurenine (TRP-KYN) pathway. Methods:The mice model was established by chronic stress. The immobility time in forced swimming test was acquired and analysed by Noldus EthoVision XT9 system. Tryptophane, kynurenine, kynurenic acid, quinaldinic acid and corticosrone in serum were detected by HPLC-MS/MS technique. The mRNA expression level of TDO in liver was detected by real-time PCR. Results:After five days chronic stress, the immobility time of model group mice was prolonged. The serum corticosterone levels, KYN/TRP and KYN/KA specific value increased and KYN/Q specific value decreased. Tiansi Liquid, Sini Powder and Peiyuan Jieyu Decoction could shorten the immobility time of mice (P<0.1). It could also cut the corticosterone levels (P<0.05); increased KYN/TRP and KYN/Q specific value (P<0.05) and reduced the KYN/KA specific value. Conclusion:Sini Powder, Tiansi Liquid and Peiyuan Jieyu Decoction have antidepressant effect. The mechanism may be related to the increase of serum corticosterone induced by stress reaction and the reduce of neurotoxicity during the TRY-KYN metabolim and improvement of nerve protection.