Abstract: Skin mucus immunoglobulin was purified by the methods of ammonium sulfate precipitation, HiTrap rProteinA Sepharose affinity chromatography and Sepharose 4B linked with mouse monoclonal antibody against serum IgM affinity chromatography from Siniperca chuatsi immersed with inactivated Aeromonas hydrophila (Ah) strain GYK1. And partial characteristics of purified proteins were analyzed and compared by SDS-PAGE and Western-blot. The results revealed that most proteins in mucus were precipitated by 50% ammonium sulfate solution, so it can only be a crude method. Determined by SDS-PAGE, Siniperca chuatsi skin mucus immunoglobulin purified by Sepharose 4B affinity chromatography has only two bands of 72 kD and 29 kD, the same two bands as which in serum. Besides the heavy chain (72 kD) and the light chain (29 kD) mentioned above, the immunoglobulin purified by HiTrap rProteinA, has a 43 kD protein band, which maybe another kind of heavy chain. Western-blot analysis showed that the rabbit polyclonal antibody can recognize bands of 72kD and 43 kD. The experiment also proved that both the methods of HiTrap rProteinA and Sepharose 4B affinity chromatography were effective to purify proteins in small quantity, whereas the contents were relatively low.