Abstract: A proteolytic activity was detected in the developing oocytes of Helicoverpa armigera. The optimum Ph was in the acidic region. The activity could be inhibited by E-64, pepstatin and iPr₂P-F. A highest hydrolysis rate was detected at Ph 4.0 when bovine hemoglobin was used as substrate. The antiserums to the cysteine proteinase and aspartic proteinase of Philosamia cynthia ricini could recognize the antigenes in the oocytes of H. armigera. The results suggested that there might be cysteine proteinase, serine proteinase and aspartic proteinase in the oocytes ofH. armigera, and these proteinases are similar to those in P. cynthia ricini.