Objective. To investigate the influence of allogeneic spleen tissue transplantation with low-dose FKS06 on allograft tolerance in rats receiving orthotopic liver transplant and the related mechanism. Methods： Female Brown Norway （BN） rats were divided into 5 groups （eight rats in each group）. Rats in Group 1 received orthotopic allogeneic liver transplantation using inbred Lewis rats as donors. Rats in Group 2 received Lewis liver transplantation＋ low-dose FK-506 （0.25 mg/kg FK-506 was orally given after transplantation）. Rats in Group 3 received Lewis liver transplantation＋ Lewis spleen transplantation. Rats in Group 4 received Lewis liver transplantation＋ Lewis spleen transplantation＋ low-dose FK-506. Rats in Group 5 received Lewis liver＋SD spleen transplantation＋low-dose FK-506. The survival periods were recorded for each group. The forming of chimerism, the responsiveness of T cells to alloantigen and the pathological changes of transplanted liver were analyzed after treatment. Results： Compared with rats in other groups, rats in Group 4 had an obviously longer survival time, an obviously reduced T cell responsiveness to alloantigen, and obviously increased donoro-positive cells （remained for 60 days after transplantation） （P〈0.05）. There was no significant pathological evidence of rejection. Conclusion： Allogeneic spleen transplantation combined with low-dose FKS06 treatment can induce graft immune tolerance in orthotopic allogeneic liver transplant recipients through promoting the formation of chimerism and T cells hyporesonsiveness to alloantigen