Glycosaminoglycan (GAGs) are sulphated polysaccharides which can bind to multiple proteins. Heparan sulfate (HS) and chondroitin sulfate (CS) are two representative GAGs and the interactions between proteins have been implicated in cancer, viral infection and Alzheimerâs disease. Due to the heterogeneous and complex structure of GAGs, the structural requirements for protein binding are less defined. The chemical synthesis of GAGs fragments, which can offer structurally-defined oligosaccharides, is required for exploring GAGs-protein binding properties. This thesis presents the development of the chemical synthesis of HS/CS oligosaccharides based on glucuronic acid (GlcA) unit. Exploring building blocks applicable to the oligosaccharide with different protecting groups were developed. These protecting group can be selectively deprotected. This method allows for preparing more types of HS/CS oligosaccharide units in fewer synthesis steps. Two types of amine tag were designed for fluorescence detection and magnetic nanoparticles (MNPs) conjugation. These works will help to investigate HS/CS oligosaccharides in the biological application in future research.