Objective To establish an acute liver congestion model in rats and evaluate changes in liver viscoelasticity during acute congestion using shear wave elastography.Methods Fourteen male SD rats with average body weight of（300±20） g were selected to establish an acute congestion liver model by ligation of retrohepatic inferior vena cava.Shear wave elastography was applied to measure liver viscosity and elasticity of rats in vivo at three time points: before ligation, after ligation, and after ligation release. The differences in the above parameters across different states were compared. The correlation between liver viscosity and elasticity values was analyzed. Additionally, changes in liver viscosity and elasticity values under acute liver congestion were assessed. Results After ligation，the viscosity and elasticity of rat livers significantly increased compared to pre-ligation（P＜0.001）.After release of the ligation，the hepatic viscosity and elasticity significantly decreased compared to post-ligation levels（P＜0.001）.There was no significant difference in the viscosity and elasticity of rat livers between pre-ligation and post-release.Correlation analysis showed a positive correlation between viscosity and elasticity of rat liver（r=0.902，P＜0.001）.In the state of acute hepatic congestion，the ratios of increase and decrease in liver elasticity in rats were significantly higher than the ratios of change in viscosity(t=5.63, 5.49, both P＜0.001).After ligation，the peak time of rat livers viscosity was 110s（95% CI：92s~128s）and the peak time of rat livers elasticity was 122s（95% CI：106s~138s）.Conclusion Shear wave elastography can be used to assess changes in liver viscoelasticity in rats with acute congestion. In the acute liver congestion state, both liver viscosity and elasticity parameters are elevated. After the release of liver congestion, these viscoelastic parameters can return to normal levels.