Abstract: In order to study the immune enhancement effect of Epimedium polysaccharide and Gynostemma polysaccharide on PRRSV attenuated vaccine, in vitro experiments were conducted to determine the safety of Epimedium polysaccharide and Gynostemma polysaccharide on Marc-145 cells, as well as their resistance to PRRSV infection. In the in vivo test, 32 10-day-old piglets were divided into 4 groups by a completely random method, namely the blank control group, the Epimedium polysaccharide group（before immunization by oral administration of 150 mg/kg body weight for 3 consecutive days, once a day）,and the Gynostemma polysaccharide group（before immunization by oral administration of 150 mg/kg body weight for 3 consecutive days, once a day）,and the vaccine control group. Except for the blank control group, the other groups were immunized with the PRRSV attenuated vaccine at 14 days of age, and the serum antibody levels, IFN-γ and IL-12 levels before immunization and 7,14,21,28,and 35 days after immunization were measured, and the serum neutralizing antibody titers were determined on 28 and 35 days after immunization. The results showed that the maximum safe concentrations of Epimedium polysaccharide and Gynostemma polysaccharide on Marc-145 cells were 62.5 μg/mL and 125 μg/mL,respectively; the anti-infective concentrations of Epimedium polysaccharide and Gynostemma polysaccharide against PRRSV were 31.25 μg/mL and 62.5 μg/mL,respectively. The Epimedium polysaccharide group had significantly higher serum antibody levels than the vaccine control group on 14,21,28,and 35 days after immunization（P＜0.05）;on 28,35 days after immunization, the levels of IFN-γ,IL-12 and were significantly higher than that of the vaccine control group（P＜0.05）. On 28,and 35 days after immunization in the Gynostemma polysaccharide group, the serum antibody level and the IFN-γ content were significantly higher than that of the vaccine control group（P＜0.05）,on 21,28,and 35 days after immunization, the IL-12 content was significantly higher than that of the vaccine control group（P＜0.05）;the serum neutralizing antibody titer in the Gynostemma polysaccharide group and Epimedium polysaccharide group were no significantly with that of the vaccine control group（P＞0.05）. The results suggested that Epimedium polysaccharide and Gynostemma polysaccharide both had a good immune enhancement effect on the PRRSV attenuated vaccine.