Objective <p>MicroRNAs hold great potential as biomarkers for assessing the progression of acute pancreatitis (AP). This study aimed to explore the value of miR-146b-5p in the diagnosis and prognosis of AP patients.</p> Methods <p>110 AP patients were included and divided into 40 severe AP (SAP) patients and 70 non-SAP patients based on disease severity. Serum miR-146b-5p levels were measured using RT-qPCR. The diagnostic value of miR-146b-5p was evaluated utilizing ROC curves. Pearson correlation coefficient was employed to analyze the correlations between APACHEII, BISAP, and MCTSI scores and miR-146b-5p levels. The AP cell model was constructed by treating AR42J cells with deoxycholic acid (DCA), the proliferative capacity of cells was measured with CCK-8, apoptosis was measured by flow cytometry, and IL-6 and IL-8 protein levels were analyzed by ELISA.</p> Results <p>Serum miR-146b-5p levels were decreased in SAP and unfavorable patients. Serum miR-146b-5p was able to effectively differentiate between SAP and non-SAP patients, and also effectively differentiate between unfavorable and favorable patients. MiR-146b-5p levels were significantly negatively correlated with APACHEII score (<i>r</i>=-0.6676), BISAP score (<i>r</i>=-0.5696), and MCTSI score (<i>r</i>=-0.5857). Furthermore, in the AP cell model, miR-146b-5p expression was down-regulated, proliferative capacity was diminished, apoptosis was increased, and IL-6 and IL-8 levels were elevated, but overexpression of miR-146b-5p partially reversed these changes.</p> Conclusion <p>miR-146b-5p expression is down-regulated in the serum of SAP patients and cells, and it has a good diagnostic effect. It may be a potential biomarker and therapeutic target for AP.</p>