Many of the most valuable pharmaceuticals are secreted recombinant proteins. Many secreted proteins often require post-translational modifications including glycosylation for their biological activities and stabilities. The glycoprotein, human erythropoietin (hEPO), is a principal growth factor responsible for stimulation of the proliferation and differentiation of responsive bone marrow erythroid precursor cells to more mature erythrocytes. Native hEPO is characterized by three N-linked complex tetra-antennary oligosaccharides (24, 38, and 83 residues) and one O-linked oligosaccharide at 126 residue. These glycans, especially N-glycans, play an important role in the biological and physical activities of the protein by controlling the secretion or biological function. An alternative plasmid-based non-lytic expression system has been developed in the insect cell line, Schneider S2 cells derived from Drosophila melanogaster. In this system, high copy numbers of recombinant plasmid vectors can be inserted into host cell genome without cell destruction. Here, we investigated the secretion and detailed N-glycan structures of recombinant hEPO produced in an insect Drosophila S2 cell suspension culture and then its N-glycans were analyzed by HPLC and MALDI-TOF. Also, we use multiple protein expression platform for several glycosylation enzymes induction or regulation. As a result, we knew that N-glycans from S2 cells were simple core structures and expression and repression of some enzymes that participated in N-glycosylation should be needed. Therefore, these enzymes will be inserted by gene cloning and then N-glycan structures will be analyzed.