Objective To explore the effects of astragalus polysaccharide combined with radiotherapy on radiosensitization of H22 transplanted hepatocarcinoma and immunologic function in mice. Methods Establishment of mouse H22 transplanted tumor model， 50 mice were divided into A group（control group）， B group（chemotherapy group）， group C（low dose of Astragalus Polysaccharides combined with chemotherapy group）， group D（middle dose chemotherapy group）， E group（Gao Jiliang chemotherapy group）， the growth situation and change observation on the immune function of tumor mice. Results With the increase of drug concentration combined with astragalus polysaccharide， TGT3， TGD and EF values were increased； treatment of 14d， the tumor weight of mice in treatment group were lower than A group and E group， and lower than the other groups， with the increase of drug concentration of Astragalus， the inhibition rate is higher； the average survival period of all treatment groups were longer than that of group A， and with the increase of drug combined with astragalus； the index of immune function in mice in each treatment group were lower than those in A group， and the combined use of Astragalus polysaccharide. Conclusion Astragalus polysaccharide combined with radiotherapy has radiosensitizing effect， can inhibit tumor growth， prolong the survival time of mice with transplanted tumor and increase the immunological function of mice.