Non⁃classical 21⁃hydroxylase deficiency（NC⁃21OHD）is one of the most frequent autosomal recessive hereditary diseases. Its phenotype is usually considered diverse and lack specificity，such as polycystic ovarian syndrome（PCOS）and frequently misdiagnosed. Meanwhile，evidence ⁃ based diagnosis and follow ⁃ up management strategies faces many difficulties and many controversial scientific problems due to NC ⁃ 21OHD. We systematically discuss the clinical features，diagnosis and therapy to improve the awareness of the disease.