Abstract: To explore the optimization concentration of ethephon on the germination of corn seeds under drought stress, corn seeds were soaked by ethephon with the concentrations of 0 mg/L, 100 mg/L, 200 mg/L, 400 mg/L and 800 mg/L respectively for 24 hours. After that, the corn seeds were treated with PEG6000 for 7 days respectively for the simulation of different drought stress. The concentrations of PEG6000 were 0%, 5%, 10% and 15% respectively. And then, the germination rate, seedling length, MDA content, CAT activity and POD activity of the corn seedling under the double stress of every treatment were determined. And the variance analysis and multiple comparisons were used to study the relationship of different treatments. The results showed that (1) the germination rate, seedling length; CAT activity and POD activity of the corn were enhanced with the ethephon of 100-800 mg/L under the same PEG6000 drought stress, and the seedling MDA content were reduced with it. (2)There were significant differences (P<0.05) between 200 mg/L ethephon treatment and 0 mg/L ethephon treatment at the same PEG6000 concentration on each determined index. Therefore, 200 mg/L ethephon could alleviate the drought stress of the corn seedling simulated by PEG6000 with the concentrations of 5%-15%.