Background. 3β-HSD deficiency is a rare type of congenital adrenal hyperplasia (CAH), which is caused by HSD3B2 gene mutations.Objectives. In order to improve the understanding and diagnosis of the disease, we analyzed and summarized the clinical characteristics, genetic variants and treatment for 3 children with 3β-HSD deficiency in this study. Materials and methods.A summary of the clinical data, hormone levels (17-hydroxyprogesterone, adrenocorticotropic hormone, cortisol, testosterone, dehydroepiandrosterone, androstenedione, renin, and aldosterone), therapeutic drugs, and gene sequencing results from 3 3β-HSD deficiency patients was created.Results. The 3 patients developed external genital abnormalities and adrenal insufficiency in infancy. Steroid hormone levels were consistent with 3β-hydroxysteroid dehydrogenase deficiency. Gene sequencing for the 3 patients detected complex heterozygous mutations in the HSD3B2 gene, which confirmed the diagnosis of 3β-HSD deficiency type II. Among the mutation types, c. 154_162delinsTCCTGTT and c.674T>A have not been reported in the literature. The 3 children were treated with glucocorticoid and mineralocorticoid replacement, which controlled the adrenal insufficiency satisfactorily. In 2 male patients, external genital dysplasia manifested as hypospadias and small penis. After long-acting testosterone intramuscular injection to increase the penis size, the hypospadias were repaired. Mild masculinization in the female patient resulted in skin pigmentation and clitoral hypertrophy; however, no surgical intervention was required. Conclusions.The main clinical manifestations of 3β-HSD deficiency were adrenal insufficiency and sex hormone synthesis dysfunction. There was a strong phenotype correlation between the observed clinical manifestations in conjunction with steroid hormone levels and HSD3B2 mutations. The novel mutations c. 154_162delinsTCCTGTT and c.674T>A were classified as pathogenic variants. Adrenal cortical function control was satisfactory after hormone replacement therapy, and hypospadias and small penis were attenuated using testosterone replacement therapy during mini-puberty for optimal surgical outcome.