Abstract: Objective To study the clinical features and gene mutations of non-classical 21-hydroxylase deficiency. Methods One case diagnosed with non-classical 21-hydroxylase deficiency with a nodule in adrenal gland in our hospital in 2014 was enrolled in this study. The clinical characteristics, diagnosis, treatment and gene analysis were reported and its related literatures were reviewed. Results The patient had menstrual disorder. Physical examination showed abnormal habitus, obesity, mild virilizing and clitorism. Radiological imaging demonstrated a nodule in her left adrenal gland. Hormonal examinations found that the patient had high androgen hematic disease and hyperinsulinemia, elevated 17- hydroxyprogesterone and testosterone level, and moderate dose dexamethasone inhibited 17-hydroxyprogesterone and testosterone. Her brother was short stature and her daughter had clitorism. All clinical manifestation mentioned above supported congenital adrenal cortex hyperplasia: non-classical 21-hydroxylase deficiency.Sequencing analysis reviewed that the patient and her daughter had the common mutation of CYP21A2 (P030L, I172N et al.). Conclusion Non-classical 21-hydroxylase deficiency is frequently misdiagnosed and 17-hydroxyprogesterone should be a routine screening in patients with a nodule in adrenal gland or hyperplasia. Parental genetic mutations can pass on to their offspring, so clinicians should pay attention to the offspring in the diagnosis and treatment of non-classical 21-hydroxylase deficiency, which can help with early detection and treatment of this disease.