11β-hydroxylase deficiency is one of the main causes of congenital adrenal hyperplasia (CAH) . It is caused by the mutation of CYP11B1 gene that encodes the enzyme. Researches have shown that mutations of CYP11B1 gene would result in activity decrease or inactivation of the enzyme in classical 11β-hydroxylase deficiency. And the relationship between genotype and phenotype of 11β-hydroxylase deficiency is not clear.