Objective To study the effect of a polysaccharide from cuscuta chinensis lam (PCCL) on antisenility and its mechanism. Methods Sixty Kunming mice were randomized into 6 groups. The three PCCL groups were administrated with PCCL of 100, 200, 400 mg?kg -1?d -1 orally, the positive control group with vitamin E of 200 mg?kg -1?d -1, the model group and control group with the same volume of control solution only. At the same time, the model group, the positive group and the three PCCL groups were subcutaneously injected of 5% D-gal at the dose of 0.5 ml at the nape, and the control with the same volume of saline solution. Seven weeks later, the MDA, SOD activity, GSH-PX activity in the liver and kidney of mice and lipofuscin (LF) in mouse brain were detected with the methods of TBA, Nitrate, DTNB and Sohal, respectively. The data were analyzed with SPSS software and the data between groups were analyzed with one-factor variance analysis. Results Thymus index and spleen index dropped, LF rose in brain, malondialdehyde (MDA) content rose and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) dropped in liver and kidney in senile mouse model. PCCL administration of 100, 200, 400 mg?kg -1?d -1 made thymus index and spleen index rising, LF dropping in brain, MDA content dropping,SOD and GSH-PX LF rising in liver and kidney of senile mouse model. Conclusion PCCL may postpone senility, which mechanism probably connected with rising immunity, eliminating oxygen free radicals and antilipoperoxidation.