In order to provide scientific rational evaluation for PCV2 infection and vaccine evaluation in large-scaled swine farms，a mature real-time PCR assay was designed and was used to quantify viral load in before and after immunized serum samples，so as to evaluate the immunity status on different domestic PCV2 vaccine. The results showed that the effect on reducing viral load of vaccines from 4 manufacturers varied significantly. The effect of prokaryotic expression vaccine of PCV2 was the best，of which the percentage decline was 97.78%，and the discretization was 49.8. In addition，PCV2 vaccine could both decrease PRRSV antibody levels and control PRRSV infection in pig farms. The results showed that the reduction of PCV2 viral load was the key to control PCV2 infection. The antibody level couldn't be the standard to estimate vaccine efficacy and there was a big difference of vaccine effectiveness from different manufactures.