Objective: To explore the diagnostic efficacy of the ratio of serum aspartate aminotransferase to alanine aminotransferase in the differentiation of fibrosis staging in patients with non-alcoholic steatohepatitis. Methods: 120 patients with non-alcoholic steatohepatitis diagnosed by liver biopsy from February 2023 to February 2025 were selected as the research subjects. The fibrosis stage of liver tissue was evaluated according to the METAVIR scoring system, and the patients were divided into F0-F1 stage, F2 stage and F3-F4 stage based on the different degrees of fibrosis. Collect and compare the baseline data of patients with different degrees of fibrosis. The receiver operating characteristic curve was used to analyze the diagnostic efficacy of the AST/ALT ratio for different fibrosis stages. Result: Among the 120 patients, 42 cases were in stage F0-F1, 35 cases were in stage F2, and 43 cases were in stage F3-F4. There were no significant differences in age, male gender, BMI, combined diabetes, combined hypertension, and combined dyslipidemia among patients with different fibrosis stages (P>0.05), but elderly patients and those with high BMI were more prone to severe fibrosis. The ratio of AST/ALT significantly increased with the aggravation of fibrosis (P<0.001). The area under the curve of the AST/ALT ratio for differentiating moderate fibrosis was 0.821, the optimal cut-off value was 0.85, the sensitivity was 74.42%, and the specificity was 78.60%. The area under the curve for differentiating severe fibrosis was 0.889, the optimal cut-off value was 1.05, the sensitivity was 81.44%, and the specificity was 85.73%. Conclusion: The AST/ALT ratio is closely related to the degree of fibrosis in non-alcoholic steatohepatitis and has a good diagnostic efficacy for moderate to severe fibrosis.