In our previous work, we have quantified the sequence-function relationship of RyhB on repressing the translation of sodB and found the exponential correlation between the fold repression and duplex formation energy AE [1].Lower AE means that sRNA and mRNA can form more stable duplex from thermodynamics, which benefits the regulation of sRNA on mRNA.Here we use RyhBt, a simpler mutant of RyhB, to further study the sequence-function relationship of sRNA.The experimental results demonstrate that the exponential correlation could be universal in sRNA-mediated gene silencing, but still some RyhBt mutants as RyhBt_7 show weak repressions than expected.