Objective. This study is to investigate the functional mimicry by using anti-idiotypic antibodies of enzymes.Results.Eight hybridomas strains secreting anti-idiotypic antibodies were selected and characterized. It was shown that two of eight anti-idiotypic antibodies secreted by two hybridomas(1A10C9 and 2A11 C1B3) could mimic HEL catalytic activity to lyse Micrococcus lysodeikticus and that the catalytic effect of mixed anti-idiotypic antibodies of 1A10C9 and 2A11C1B3 was stronger than that of one of them, but less than HEL.Conclusion. The results demonstrated that the anti-idiotypic antibodies that could mimic enzyme activity existed in the idiotype network during anti-enzymatic immune response.