Chemical synthesis of proteins containing up to 300 amino acids may cover 30％-50％ of all the proteins encountered in biomedical studies and may provide an alternate approach to the usually used recombinant expression technology,vastly expanding the chemical space of the latter.In the present review article,we tried to survey the recent progresses made for more rapid synthesis of increasingly long peptides and more efficient ligation of multiple peptide segments.The developments of seminal methods by many research groups have greatly contributed to the recent breakthroughs in the successful total synthesis of a number of functionally important proteins,such as oligoubiquitins,bacterial GroEL/ES chaperones,and mirror-image DNA polymerases.Through these studies,a potential bottleneck has also been recognized for the chemical synthesis of large proteins,namely,how to ensure that each peptide segment from a large protein avoids unfavorable aggregation when dissolved in aqueous solution.Many new methods,such as removable backbone modification(RBM) strategy have been developed to overcome this bottleneck,while more studies need to be carried out to develop more effective and less costly methods that ultimately,may lead to fully automatable chemical synthesis of customized proteins of 300 amino acids bearing any artificial designs.