Abstract: Objective:To study the effect of β-Eleostearic acid on the apoptosis of human choriocarcinoma JEG-3 cells and its relative mechanisms. Methods:JEG-3 cells were treated with different concentrations of β-eleostearic acid.MTT was used to detect the relative activity of cells.The release of lactate dehydrogenase (LDH) was detected according to the instructions to analyze the toxic effect of β-eleostearic acid on JEG-3 cells.Flow cytometry and western blotting were used to analyze the apoptosis of JEG-3 cells.The reactive oxygen species (ROS) level was determined by the fluorescence intensity of 2', 7'-dichlorofluorescein (DCF). ROS inhibitor N-acetyl-L-cysteine (NAC) was used to analyze the role of ROS in the effect of β-eleostearic acid on the relative activity of JEG-3 cells. Results:β-eleostearic acid could inhibit the relative activity of JEG-3 cells in a dose-dependent and time-dependent manner (P<0.05). β-eleostearic acid significantly promoted the release of LDH and promoted the apoptosis of JEG-3 cells (P<0.05), and the expression level of apoptosis related protein Caspase-3 and the expression ratio of Bax/Bcl-2 were up-regulated.It proved that β-eleostearic acid could induce the apoptosis of JEG-3 cells. In addition, β-eleostearic acid could increase the content of ROS in JEG-3 cells. The inhibitory effect of β-eleostearic acid on the relative activity of JEG-3 cells could be antagonized by ROS inhibitor NAC (P<0.05). Conclusion:β-eleostearic acid could induce the apoptosis of JEG-3 cells.Its effect was likely related to the production of ROS.