MiRNAs are widely recognized as biomarkers of many diseases. Many studies have shown that, miRNA-155 in patients with breast cancer in the body was significantly higher than normal people. After a thorough literature review , we know the recognition site of miRNA-155, of which the transcription product, mRNA and miRNA-155 base-specific complementary matching, in order to increase its binding specificity with miRNA-155, we design four binding sites for this part, so that when the miRNA-155 presence, it can be quickly identified by this fragment and combine to form double-stranded mRNA complex, blocking the binding of ribosomes, which will inhibit the downstream gene expression, which is called RNA-based gene silencing expression. This can serve as a switch to regulate the expression of downstream genes.