Abstract: Oligosaccharides play important roles in many biological processes and have great medicinal potential. The structure-activity study of oligosaccharides is complicated by the diversity and complexity of their structures. This review summarizes the state of oligosaccharide structural analysis in recent years. The ionization methods and dissociation rule of acid oligosaccharides, neutral oligosaccharides and glycopeptides in mass spectrometry are discussed and the methods of extraction and purification of oligosaccharides, the suitable mass spectrometry models for different types of oligosaccharides, and the advantages and disadvantages of different mass spectrometry models are introduced. We believe that this review will be helpful for the further investigation of these important biological substances.