Transjugular intrahepatic portosystemic shunt (TIPS) is a widely used surgery for portal hypertension. In clinical practice, the diameter of the stent forming a shunt is usually selected empirically, which will influence the postoperative portal pressure. Clinical studies found that inappropriate portal pressure after TIPS is responsible for poor prognosis; however, there is no scheme to predict postoperative portal pressure. Therefore, this study aims to develop a computational model applied to predict the portal pressure after TIPS ahead of the surgery. For this purpose, a patient-specific 0-3-D multi-scale computational model of the hepatic circulation was developed based on preoperative clinical data. The model was validated using the prospectively collected clinical data of 18 patients. Besides, the model of a representative patient was employed in the numerical experiment to further investigate the influences of multiple pathophysiological and surgical factors. Results showed that the difference between the simulated and in vivo measured portal pressures after TIPS was −1.37 ± 3.51 mmHg, and the simulated results were significantly correlated with the in vivo measured results (r = 0.93, p < 0.0001). Numerical experiment revealed that the estimated model parameters and the severity of possible inherent portosystemic collaterals slightly influenced the simulated results, while the shunt diameter considerably influenced the results. In particular, the existence of catheter for pressure measurement would markedly influence postoperative portal pressure. These findings demonstrated that this computational model is a promising tool for predicting postoperative portal pressure, which would guide the selection of stent diameter and promote individualization and precision of TIPS.