Abstract:As the temperature declined, the content of sulfhydryl group decreased, the electrolyte leakage increased and there was a negative correlation between the decrease of sulfhydryl group and the increase of the MDA content in the cotyledons of cucumber seedlings. The decrease of the sulfhydryl group and the increase of the MDA content in cucumber seedlings were inhibited by sodium benzoate (SB) and α-tocopherol (Vit E) pretreatment, but enhanced by methyl viologen (MV) pretreatment. The decrease of sulfhydryl group and the increase of electrolyte leakage in cucumber seedlings under Iow temperature were enhanced with the increasing of the MDA pretreated concentration, showed the MDA could have a destructive effect to sulfhydryl group. These results suggested that the decrease of sulfhydryl group was correlated with the peroxidation of the membrane lipids in cucumber seedlings under chilling stress.