Objective To investigate the effects of hydrogen on cell protection of placental ischemia-reperfusion cell model of preeclampsia and its possible mechanism. Methods JAR cells cultured in vitro were divided into five groups, i.e. the blank control group, saturated hydrogen group under normal oxygen cultivation conditions (normal oxygen+H₂ group), ischemia-reperfusion model group (model group), ischemia-reperfusion group with saturated hydrogen intervention (model+H₂ group), and ischemia-reperfusion positive control group with vitamin C intervention (model+VC group). Cells of the model group, model+H₂ group, and model+VC group were cultured with sugar and serum free medium in hypoxia (5%CO₂ and 95%N₂) environment for 2 h, and then they were cultured with high sugar and 10% serum medium in the environment of 95% air and 5% CO₂. The ischemia-reperfusion cell model was established. The hydrogen intervention and vitamin C intervention were performed during the hypoxia period and reoxygenation period, respectively. After cells were cultured in the complete medium for 24 h, the cell survival rate was detected by the MTT method; the content of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) were measured by the chemical olorimetry; and the expression of SOD mRNA was detected by the Real-Time PCR. After cells were cultured in the complete medium for 1 h, the intracellular ROS level was measured by the DCHF-DA fluorescence. Results Compared to the model group, the cell survival rate of the model+H₂ group increased (P<0.05); the ROS generation (P<0.01) and MDA content (P<0.05) decreased significantly; and the SOD activity (P<0.01) and the expression level of SOD mRNA (P<0.05) increased. Conclusion Hydrogen has the protective effect on the placental ischemia-reperfusion cell model of preeclampsia. The mechanism may be the reduction of cell oxidative stress level by up-regulating the transcription of SOD-mRNA, increasing the activity of SOD, and decreasing the level of intracellular reactive oxygen.