[Abstract] Objective This study investigated the diagnostic efficacy of ultrasound-derived fat fraction (UDFF) in non-invasively assessing the degree of hepatic steatosis in obese people, using pathological and histological findings as the gold standard. Methods A total of 70 obese subjects, including 15 males and 55 females, who underwent ultrasonography and found fatty liver with hepatic histopathological findings in the First Affiliated Hospital of Shandong First Medical University from April to December 2023 were collected. The consistency and variability of UDFF values and their correlation with clinical indicators and measurement depth were analysed to assess the diagnostic efficacy of UDFF for different degrees of hepatic steatosis. Results The UDFF values of groups S1, S2, and S3 were 17.08±7.15%, 24.80±5.22%, and 28.48±5.22%, respectively, and the differences in the UDFF values of different grades of fatty livers were statistically significant (P＜0.05).The UDFF values were significantly and positively correlated with the pathological fat grades (r=0.638, P＜0.01), and moderately with the measurement depth (P＜0.01). depth of measurement moderately (r=0.313, P＜0.01), weakly correlated with BMI, waist circumference, and abdominal wall thickness (r=0.236, 0.248, 0.236, P=0.049, 0.038, 0.050), and did not correlate with age, fasting glucose, triglycerides, total cholesterol, HDL cholesterol, and LDL cholesterol (r= 0.138, 0.022, -0.027, 0.064, 0.074, 0.076, Pall＞0.05).The area under curve (AUC) of UDFF for diagnosis of S2 and above and S3 and above were 0.86, 0.82, with the sensitivity of 91.1%, 88.0%, specificity of 72.0% and 68.9%, and the positive cut-off values were 20.5% and 23.5%, respectively. Conclusion The UDFF technique has good diagnostic efficacy in assessing the degree of hepatic steatosis in obese people.