Systemic therapy with cytotoxic agents remains one of the main treatment methods for non-small-cell lung cancer (NSCLC). Cisplatin is a commonly used chemotherapeutic agent, that, when combined with other drugs, is an effective treatment for NSCLC. However, effective cancer therapy is hindered by a patient’s resistance to cisplatin. Unfortunately, the potential mechanism underlying such resistance remains unclear. In this study, we explored the mechanism of microRNA-106b-5p (miR-106b-5p), which is involved in the resistance to cisplatin in the A549 cell line of NSCLC. Quantitative real-time PCR was used to test the expression of miR-106-5p in the A549 and the A549/DDP cell line of NSCLC. The cell counting kit-8 assay was used to detect cell viability. Flow cytometry was used to measure cell cycle and cell apoptosis. Luciferase reporter assays and western blot were performed to confirm whether polycystic kidney disease-2 (PKD2) is a direct target gene of miR-106b-5p. Immunohistochemistry was performed to examine the distribution of PKD2 expression in patients who are sensitive and resistant to cisplatin. The experiments indicated that the expression of miR-106b-5p was significantly decreased in A549/DDP compared with that in A549. MiR-106b-5p affected the tolerance of cells to cisplatin by negatively regulating PKD2. Upregulation of miR-106b-5p or downregulation of PKD2 expression can cause A549/DDP cells to become considerably more sensitive to cisplatin. The results showed that miR-106b-5p enhanced the sensitivity of A549/DDP cells to cisplatin by targeting the expression of PKD2. These findings suggest that the use of miR-106b-5p may be a promising clinical strategy in the treatment of NSCLC.