We studied the effects of anti-infection of white spot syndrome virus (WSSV) by adding different concentrations of astragalus polysaccharides (APS) to the basal diet in Procambarus clarkii. The healthy P.clarkii which were negative of WSSV by PCR detection were injected intraperitoneally, with 100 μL WSSV, and fed with 0%, 0.2%, 0.4%, 0.8% of APS bait. After feeding 20 d, the result revealed that when the positive control group mortality rate was 100±0%, the mortality of 0.2%, 0.4%, 0.8 % APS addition groups were 86.67%±13.33%, 91.11%±7.70%, 73.33%±17.64%,respectively. In order to evaluate the effect of APS on visceral organs, such as gill, hepatopancreas, and myocardial tissue in P. clarkii, the tissue sections were observed. The results showed that there was significant pathological change like nuclear pyknosis, cell ruptured and arranged desultorily in the group of 0% APS bait, but there were no obviously pathological changes in the gills and hepatopancreas, whereas nucleoli displayed a certain degree of shrinkage, while the cells have not yet broken in the myocardial tissue in the group of adding 0.8% APS bait. This experiment showed that the survival rate can be increased to 26.67% when adding 0.8% APS bait compared with the positive control in P.clarkii. The APS can significantly improve the effect of resistance of P. clarkii to the WSSV infection, and it can be expected to receive good economic benefits in the actual aquaculture production.