Abstract: In order to isolate and purify IgG from porcine serum and prepare for its Fab fragments, Protein G affinity chromatography and octanoic acid ammonium sulfate precipitation（CA-AS） were used to purify IgG from porcine serum. Then, porcine IgG was hydrolyzed by papain to form Fab fragments, and porcine Fab and Fc fragments were separated by Protein A chromatography column, and porcine Fab was further purified by gel chromatography. The purity of porcine Fab fragment was identified by SEC-HPLC, and the activity of porcine Fab fragment was identified by ELISA and Western-blot. The results showed that the porcine IgG was successfully purified from porcine serum, and the purity of Protein G affinity chromatography was higher than that of CA-AS, with a purity of ＞95%, which could be used for the subsequent preparation of porcine Fab protein. When the enzyme/antibody ratio was 1∶10, the porcine IgG could be completely digested by papain at 15 hours. The porcine Fab fragments were further purified by Protein A and gel chromatography, and the purity of Fab fragment was ＞99% by SEC-HPLC. ELISA and Western-blot showed that Fab fragment had good activity. It indicated that porcine IgG was successfully isolated from porcine serum and Fab fragment was prepared.