X-linked adrenoleukodystrophy (ALD) is a uncommon metabolic disorder which derived by peroxismal ${eta}$-oxidation and elevation of serum very long chain fatty acid (VLCFA). VLCFA is mainly accumulated in the myelin of the central nervous system and adrenal cortex, by which the expressed symptoms of this disease are mainly neurologic and endocrinologic (such as adrenal insufficiency). The mutations in the ABCD1 gene causes X-linked ALD, nevertheless its phenotypes and genotypes are poorly coordinated. We report the case of a 12-year-old boy with X-linked ALD who developed vomiting, fatigue and poor oral intake. Severe dehydration and hyponatremia were found in initial physical examination and laboratory test, but his motor/sensory nerve function and mental status were completely normal. We diagnosed ALD with diffuse high-intensity signal in both parietotemporal cerebellar white matter in brain MRI and elevated serum VLCFA. Later, we confirmed a novel c.1635-1G>A (IVS6-1G>A) mutations of the ABCD1 gene. With the discrepancy between its phenotypes and genotypes, various phenotypes could be seen in X-ALD patient. Careful examination and further studies for these patients will be needed.