【Abstract】 Congenital adrenal hyperplasia is a group of autosomal recessive inherited diseases, which are mainly caused by the deficiencies of various catalytic enzymes in different stages of the adrenocortical steroid synthesis pathway, with 21-hydroxylase deficiency (21-OHD) as the most common disorder. In 2010, experts of the Endocrine Society Clinical Guidelines Subcommittee published the first clinical practice guideline of 21-OHD. In 2018, TES released a new version of the guide (the second edition). Now, the key points and clinical progress of the new edition of the guidelines are interpreted to provide references and strategies for clinical diagnosis and treatment of 21-OHD.