Protein glycosylation plays a key role in all aspects of life activities. Glycosylation is controlled by a variety of glycosyltransferases and glycosidases, resulting in its high heterogeneity. Chemical synthesis of glycoprotein can provide homogeneous glycoproteins. However, the process is complicated and usually provides a small amount of glycoprotein. First, we have developed a general method to prepare β-mercapto amino acids (including Leu, Glu, Gln, Lys, Phe, Arg, Trp, and Met) via a photoredox-catalyzed asymmetric Giese reaction, which can facilitate the crucial NCL-desulfurization for complex proteins. Second, 7-(piperazin-1-yl)-2-(methyl)quinolinyl (PPZQ)-assisted ligation that allows for the EPL-desulfurization approach to construct proteins bearing multiple native Cys residues in the expressed protein segment, facilitating the preparation of complex and large proteins. The two methods provide powerful solutions for the synthesis of glycoproteins such as glycoprotein d of herpes simplex virus-1.