Abstract: Chicken IL-2 is an key cytokine for immunity. Removed the signal peptide by PCR，chIL-2 gene fragments (387bp) was connected to the pPICZαA expression vector and transformed to Pichia pastoris GS115 by electroporation. SDS-PAGE and Western Blot analysis showed that chIL-2(17.8kD) was successfully expressed and secreted by positive strains induced by 1% methanol. The chIL-2, which was purified by Ni-NTA His Bind column chromatography with 250mM imidazole elution buffer, had significant biological activity to promote lymphocyte proliferation, which provides the experimental basis for the further research on chIL-2 as a kind of immune adjuvant.