The present study reports a patient case with a 17α-hydroxylase deficiency accompanied by triple X syndrome. A 17α-hydroxylase deficiency leads to a very low 17α-hydroxylated steroid synthesis as well as a non-feedback increase in the adrenocorticotropic hormone level. Meanwhile, the progesterone level increases the 17α-hydroxyprogesterone level and decreases the dehydroepiandrosterone sulfate level. The patient is characterized by intractable hypokalemia, high urinary potassium, hyperaldosteronemia, hyporeninemia, hypocortisolemia, hypertension, gonadal and secondary sexual dysplasia, a decreased estrogen level, primary amenorrhea, and infertility. The imaging findings indicate a presence of multiple bilateral adrenal gland adenomas, and the sequencing indicates a missense CYP17A1-E7 gene pathogenic variant. The karyotype is a 47, XXX [3]/46, XX [47] low-level chimeric karyotype. The patient's parents are cousins. To our knowledge, this patient is the first case diagnosed with congenital adrenal hyperplasia caused by hydroxylase deficiency and triple X syndrome. The uniqueness of this case is that this patient has two very rare genetic diseases, probably due to the marriage of close relatives.