Structure of a recombinant chimeric anti-CD20 IgG1 monoclonal antibody was verified by    the application of high-performance liquid chromatography-mass spectrometry (HPLC-MS) and N-terminal   sequencer.  Molecular masses, N-terminal sequences and peptide maps of the antibody treated with different  reagents and enzymes were measured.  Results indicate that the amino acid sequences of light and heavy chains and 10 disulfide bonds were consistent with theoretical structure.  By comparison of molecular masses and  peptide maps for the fully glycosylated and deglycosylated samples, the N-linked glycosylation site was identified.  The method is simple, rapid, precise, and could be referred to the quality control and structure determination of other IgG1 products.