Abstract: In this study, we investigated the diversities of six Litopenaeus vannameihemocyanin isomers binding to different bacteria. The methods of affinity-binding, PAGE, SDS-PAGE, Western-blotting and hemolytic activity assays were used. The results indicated that all the six hemocyanin isomers, namely hemocyanin isomer directly binding to Vibrio parahaemolyticus (HMC-VP), Vibrio alginolyticus (HMC-VA), Vibrio fluvialis (HMC-VF), Escherichia coli K12 (HMC-EC), Beta Streptococcus (HMC-BS) and Staphylococcus aureus (HMC-SA) displayed different hemolytic activities to chicken erythrocyte. Among of these, HMC-VP and HMC-SA showed the highest hemolytic activity and reached almost complete (100.00%), while that of HMC-VA was only 39.96%. To further elucidate the molecular basis underlying hemocyanin isomers functional diversities, the assays of glycosyl-oxidation and trypsin digestion were selected. The results showed that glycosyl-oxidation led to a generally significant decrease in hemolytic activity of all of the hemocyanin isomers, even completely abolished. In contrast, the hemolytic activities of these hemocyanin isomers were highly increased, even reached 100.00% after trypsin digestion. Thus, these results revealed that six hemocyanin isomers possessed different hemolytic activities, which may be related to the diversity of protein glycosylation and conformation.