PiCyt1 is a protein produced by Pseudoplusia includens (Lepidoptera: Noctuidae) that is expressed in a population of hemocytes called plasmatocytes. Because it shares significant homology with another protein, Asp-hemolysin, we hypothesize that PiCyt1 is a cytolytic protein. Here we expressed PiCyt1 into pIZT/V5-His vector and transfected High Five and Drosophila S2 insect cells. The expression level of PiCyt1 in these cell lines was tested by Western blot and immunocytochemistry. The results indicated that the expression level in Drosophila S2 cells is much higher than that in High Five cells. Through the attached 6xHis tag on the C-terminus of PiCyt1, we purified the recombinant protein by Ni²⁺-beads. The cytolytic activity of the recombinant PiCyt1 was tested against sheep, chicken and human erythrocytes. The results suggested that the recombinant PiCyt1 has cytolytic activity.