OBJECTIVE： To study the effects of Atractylodes macrocephala ethanol extract （AM） on life span of Caenorhabditis elegans（called N 2 nematode for short ），and to investigate its mechanism based on transcription factor SKN- 1/ nuclear factor E 2 related factor 2（Nrf2）. METHODS ：N2 nematode were divided into blank control group ，positive control group （100 μ mol/L curcumin，similarly hereinafter ），AM low-dose ，medium-dose and high-dose groups （100，200，300 μ g/mL， similarly hereinafter ）. The effects of AM on the life span （by average survival time ）of N 2 nematode under normal condition and oxidant stress condition （40 mmol/L H 2O2）as well as its effects on reproductive capability （by the number of filial generation ）of N2 nematode under normal condition were investigated . 700 μmol/L H2O2 was used to establish neuroblastoma cells N 2a oxidant stress model. Effects of positive control ，low-dose，medium-dose and high-dose of AM on the survival rate of model cells were detected by MTT method. After human embryonic renalepithelial cells 293T were transfected with Nrf 2-ARE plasmid ， the effects of positive control and AM on luciferase activity of Nrf2-ARE were detected by luciferase reporter gene method at low，medium and high dose for 24 h and at medium dose for 12，18 and 24 h. RT-PCR was used to detect the effects ofpositive control ，low-dose，medium-dose and high-dose of AM on the mRNA expression of downstream genes NQO- 1 and HO- 1 of Nrf 2 in N 2a cells as well as mRN A expression of en@hactcm.edu.cn downstream genes GCS- 1，GST-7，GST-10，HSP-60，HSP- 16.2 and SOD- 3 of SKN- 1 in N 2 nematode. RESULTS ：Compared with blank control group ，average survival time of N 2 nematode under normal and oxidant stress condition was significantly prolonged in positive control group and AM groups ；the number of filial generation on the first day （except for AM high-dose group ），the number of filial generation on the second day （except for AM low-dose group ） and the total number of filial generation （except for AM low-dose group ） were increased significantly（P＜0.05 or P＜0.01）. The survival rate of N 2a cells in positive control group ，AM medium-dose and high-dose groups were significantly higher than that of model group （P＜0.05 or P＜0.01）. Compared with blank control group ，Nrf2-ARE luciferase relative activity of 293T cells in positive control group and AM groups as well as Nrf 2-ARE luciferase relative activity of 293T cells in AM medium-dose group after different time of treatment were increased significantly （P＜0.01），in dose-dependent and time-dependent trend. Compared with blank control group ，mRNA relative expression of HO- 1 and NQO- 1（except for positive control group ），GCS-1（except for AM low-dose group ），GST-7（except for positive control group and AM low-dose group ）， GST-10 and HSP- 60（except for AM low-dose group ），HSP-16.2（except for positive control group and AM low-dose group ）and SOD-3 （except for positive control group and AM low-dose group ） were increased significantly （P＜0.05 or P＜0.01）. CONCLUSIONS：AM can prolong the life span of N 2 nematode under normal and oxidant stress condition and improve the its reproductive capacity ，the mechanism of which may be associated with the activation of SKN- 1/Nrf2 signaling pathway.