To establish an indirect enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to PCV2, the cap gene without nuclear localization signal peptide sequence of PCV2 was cloned into the pET28a(+) vector, and the recombinant Cap⊿41 protein was expressed in soluable form in Escherichia coli (E. coli). The optimum working conditions of the indirect ELISA were determined using Cap⊿41 protein as diagnostic antigen, and 394 pig serum samples from 4 pig farms were tested. The results showed the diagnostic sensitivity and specificity of the established indirect ELISA were 93.14% and 95.17%, respectively, compared with indirect immunofluorescence (IIF). And the inter-assay and intra-assay variations of the ELISA were low. Besides, the seroprofiles of 4 pig farms revealed by the testing results were in accordance with clinical results, indicating the established indirect ELISA is reliable and can be used for detection of antibodies to PCV2.