Protected amino acid compounds are often widely used as intermediates of drug molecules and functional material intermediates. The high efficiency of Boc-protected amino acid esters provides an important prerequisite for their subsequent conversion in the entire process. Boc-tert-butyl phenylalanine was selected as the raw material, and the process of selectively removing the Boc protecting group while retaining the protecting group of tert-butyl ester to generate tert-butyl phenylalanine hydrochloride was studied. Under room temperature or low temperature conditions, the yield of about 82% can be achieved by deprotection under acidic conditions, and the reaction conditions are simple and mild, and the cost of process equipment is low, which realizes simple operation, economical benefits and environmental protection.