We reported an 87-year-old female patient who suffered from acute kidney injury (AKI) associated with hypercalcemia crisis. The patient had a history of chronic kidney disease (CKD), with main manifestations of fatigue, anorexia, lower extremity weakness, and elevated serum creatinine (Scr) and serum calcium. We made differential diagnosis and dominant position between CKD on AKI (A on C) and hypercalcemia carefully. After further questioning the medical history combined with electrocardiographic findings, the diagnosis of vitamin D intoxication was established for the patient. All the symptoms of the patient were relieved after stopping all calcium and vitamin D preparations, being fully hydrated with appropriate diuretic, as well as salmon calcitonin intramuscularly therapy for 10d. It is suggested that attention be paid to medication education and personalized medical therapy for the elderly, especially those with CKD, and electrocardiography and other non-invasive examination are of clinical significances in early diagnosis.