Magnesium deficiency usually refers to hypomagnesemia, and the common clinical manifestations of hypomagnesemia include tetany, myoclonus, and Chvostek’s sign, etc. Hypomagnesemia usually refers to a serum magnesium concentration of less than 0.75 mmol. Hypomagnesemia usually refers to the serum magnesium concentration is less than 0.75mmol/l, mild hypomagnesemia usually does not have more obvious clinical manifestations. Moderate or severe hypomagnesemia can present clinically as early and late symptoms. Early symptoms include: nausea, vomiting, nervousness, fatigue and other symptoms. Middle and late symptoms include tetany, tremor, and Chvostek’s sign (non-random contraction of the facial muscles induced by gently tapping the nerve in front of the external auditory canal), and in severe cases, grand mal seizures. If the above symptoms of magnesium deficiency occur, it is recommended to go to the hospital as soon as possible, and standardize the treatment under the guidance of the doctor to ensure a good prognosis of the disease.