Application of transgenic Cholrella as bioreactor to express rabbit neutrophile pepetide-1 (NP-1) shows great practical value. In this paper, an NP-1 expression vector containing two selective marker genes NPTII and nitrate reductase gene was constructed. The NP-1 gene was transformed into the nitrate reductase-deficient mutant nrm-4 of Chlorella ellipsoidea via electroporation, and the transgenic alga expressed the active NP-1 were obtained.