Abstract: Objective To detect possible effect of extremely low frequency electromagnetic field(ELF-EMF)on rat astrocytes.Methods The Sprague-Dawley(SD)rat astrocytes were used as a model.The astrocytes were exposed to ELF-EMF at different intensity(2,4,6,8,10 mT)for 15,30,and 45 min,respectively.The survival rate,the morphology of astrocytes and the level of reactive oxygen species(ROS)were measured.Results Astrocytes proliferation was promoted within a certain radiation intensity and duration in the study.The most significant promotional effect was observed in the group with 10 mT for 30 min(P<0.01).Under the condition,the cell survival rate was 127.31%,and the intracellular ROS content increased with increasing magnetic field strength.When the radiation intensity was 10 mT and the duration was 30 min,the intracellular ROS reached the highest level,and the fluorescence intensity was 237.67,which was significantly higher than that of the control group(P<0.01).Conclusion Short-term ELF-EMF exposure can induce the increase of ROS in rat astrocytes,which may be one of the mechanisms of cell proliferation.