Abstract: Objective To observe the therapeutic effect of human umbilical cord mesenchymal stem cell(HUC-MSC) transplantation on patients with decompensated cirrhosis. Methods ALT,AST,TBiL,PT,ALB levels were measured in 24 patients with decompensated cirrhosis before and 1,2,4,8,12 weeks after they underwent HUC-MSC transplantation.Their clinical symptoms and adverse reactions were observed by CT before and 8,12 weeks after HUC-MSC transplantation. Results No significant improvement was found in liver function of the patients 2 weeks after HUC-MSC transplantation(P>0.05).The ALT and AST levels were significantly lower 4 weeks after HUC-MSC transplantation than before HUC-MSC transplantation((82±12)IU/L vs(106±18)IU/L,(87±14)IU/L vs(121±23)IU/L,P<0.05).No significant improvement was observed in the other liver function indications of the patients.All the indications of liver function obviously improved 8 and 12 weeks after HUC-MSC transplantation(P<0.05).The clinical symptoms of the patients alleviated with the prolongation of time.No adverse reaction occurred.The liver maximum cross-sectional area was significantly larger after HUC-MSC transplantation(P<0.05) with no significant change in CT value of liver(P>0.05). Conclusion HUC-MSC transplantation can significantly improve the liver function and clinical symptoms of patients with decompensated cirrhosis and promote their liver repair.