Abstract: Eupolyphage sinensis Walker adults (female) were injected with 5 μL E.coli、Staphylococcus aureus and Bacillus subtilis respectively via intravitreal injection. The antibacteial activity of haemolymph extracted from induced Eupolyphage for 24, 48 and 72 h respectively to the three bacterial was measured with the filter paper method and compared with the uninduced Eupolyphage as the negative control. The strongest antibacterial activity of haemolymph induced by Staphylococcus aureus for 48h was chosen and then the influence on haemolymph of such factors as the increased sample, pH, temperature and heating time  were analyzed. The results show that the antibacterial activity of hemolymph enhances with the increasing amount of  the sample; The optimal pH value is 5.0； the antibacterial activity of hemolymph is sensitive to heat，and there is no action at the temperatures of 80 ℃ or 100 ℃ within a short period.

Key words: Eupolyphage;  haemolymph;  inducement； antibacterial activity