BACKGROUND:?Small-for-size (SFS) syndrome is an important clinical problem after living donor liver transplantation, split liver transplantation or extended hepatectomy. The uncertainty of the mechanisms and treatments of SFS syndrome urges surgeons to establish effective models for SFS syndrome. METHODS:?A new porcine model for SFS syndrome based on extended hepatectomy was established. Portal pressure gradient was observed before and after the surgery, and venous sampling for estimation of alanine aminotransferase, total bilirubin, and international normalized ratio was continued on a daily basis. RESULTS:?Although the external morphology of the porcine liver differs from that of human being, segmental anatomy is remarkably similar in term of its vascularity and biliary tree. Extended hepatectomy with segmentsⅠandⅦas resection remnant (about 20%of total liver volume) resulted in similar survival rates, blood liver function tests, and elevated portal pressure gradient as clinical SFS syndrome. CONCLUSIONS:?The extended hepatectomy based new model can easily be reproduced, with few costs and surgical complications. Clinical SFS syndrome can easily be simulated by this new model, which is a useful tool for studying SFS syndrome-related liver injuries, especially portal overperfusion and hypertension.