Abstract: The miRNA398 in model plants could repress the expression of Cu/Zn-SOD gene.In order to reveal the biological function of miRNA398,fluorescent quantitative PCR(qPCR) technology was employed to analyze the expression levels of miRNA398 and Cu/Zn-SOD gene in cv.CB-1 and B37 under drought stress.Meanwhile,the locus where miRNA398 combining with Cu/Zn-SOD gene was also predicted.The results showed that miRNA398 was complementary to a 21 bp sequence in 5'untranslated region of Cu/Zn-SOD gene,thereby to repress the expression of Cu/Zn-SOD gene.Under drought stress,the expression level of miRNA398 was up-regulated in CB-1 and down-regulated in B37,while that of Cu/Zn-SOD gene was on the contrary;which indicated that miRNA398 repressed the expression of Cu/Zn-SOD gene and responsed to drought stress in two different ways in the two varieties of different resistance to drought.