A reliable and efficient method for the determination of N-glycan structures in glycoprotein was developed by the combination of two dimensional offline liquid chromatography and exoglycosidase sequencing.Firstly, the N-glycans at different sialylation degrees were prepared by weak anion exchange chromatography,then the structures of analytes were identified by capillary electrophoresis-laser induced fluorescence detection(CE-LIF) combined with exoglycosidase digestion.After fluorescent labellling,the structural annotation was performed by the top-down digestion and the bottom-up identification,and a total of 18 N-glycan structures in Immunoglobulin G(IgG) were identified.Finally,the same method was applid in the analysis of N-glycans in human serum samples.The ratio for monosialylated,disialylated,trisialylated and tetrasialylated degree was 4.7∶20.9∶6∶1Results showed that high abundance neutral sugar chains in human serum were very similar to those in IgG in structure,and the disialylated N-glycan structure FA2G2S2 was the most abaundent in serum N-glycan pool.The method had an application potential in N-glycosylation analysis.