Magnesium sulfate is often used clinically for fetal preservation drug treatment, this drug has the effect of relieving smooth muscle spasm, can effectively relieve the condition of strong contractions in pregnant women, thus can play an effective role in fetal preservation. Most patients in the use of magnesium sulfate fetus about 3-5 days the condition can be significantly relieved, the general patients use magnesium sulfate time will not exceed a week. When pregnant women use this drug, need to pay close attention to the pregnant woman’s breathing, urine volume, and tendon reflexes to determine whether there is an overdose of the situation. If the patient’s breathing is weakened, the urine volume is reduced, the knee reflex disappears, it means that the drug is overdosed, and the possibility of drug poisoning is not excluded. In case of drug intoxication, the patient should be treated with calcium gluconate or other medications.