Exosomal microRNAs (miRNAs) are among the most common biomarkers for tumor diagnosis. However, singlemiRNA detection lacks ideal sensitivity and specificity for diagnosing a certain tumor in clinics. In this work, we fabricated a convenient multi-miRNA detection platform for sensitive and specific detection on exosomal miRNAs in the plasma of patients using a terahertz (THz) metamaterial biosensor on the basis of strand displacement amplification (SDA) and AuNPs. The proposed multi-miRNA detection platform was highly sensitive to miRNA15, miRNA-21, miRNA-145, miRNA-155, miRNA-423, and miRNA-451, and the limit of detection (LOD) obtained were 12.54 aM, 19.66 aM, 17.50 aM, 25.40 aM, 24.11 aM and 26.59 aM, respectively. The biosensor we constructed can be used to diagnose pancreatic cancer patients effectively in complex clinical samples. The use of multiple miRNAs demonstrated strong practicality in the combined diagnosis of patients with pancreatic cancer. These studies demonstrate that the multi-RNA detection platform boasts advantages such as low cost, rapid, high sensitivity, and specificity, offering a potential tool for future clinical applications.