Objective To assess the ability of quantitative ultrasound index to predict the severity of CCl4?induced liver fibrosis in a rat model us?ing logistic regression analysis. Methods In a rat model of 40%CCl4?induced liver fibrosis,ultrasound detected the portal vein diameter,blood flow velocity,and Young's modulus. The degree of hepatic fibrosis was determined using a light microscope after hematoxylin and eosin staining of tissue. Results Portal vein diameter and Young's modulus were useful predictors of the severity of liver fibrosis,with statistical significance(P<0.05). Young's modulus was most effective with an R2 value 0.788. Young's modulus combined with the distal diameter of portal vein effectively improved the predictive ability,showing an R2 value 0.821. Conclusion Young's modulus is the most predictive index to assess the severity of liver fibrosis. A combination of multiple indices can improve the ability to predict the severity of liver fibrosis.