Magnesium sulfate is a kind of hypertonic salt solution, with hypertonicity, anti-inflammatory, de-swelling effect. Its main mechanism of action is: I. Magnesium sulfate uses local high osmotic pressure effect to transfer intracellular water to extracellular, so that the local inflammatory edema of tissue cells in a dehydrated state, reduce the swelling of the lesion, to achieve the role of relieving swelling and pain. Second, magnesium sulfate can improve the activity of local lymphocytes, inhibit the reproduction of bacteria in the wound, increase the ability of the granulation tissue to fight infection, and is conducive to the subsidence of inflammation. Third, magnesium sulfate can increase local blood circulation, improve the nutritional status of local tissues, and promote wound healing. Clinically, magnesium sulfate is often used as a topical treatment for superficial phlebitis, dengue, and also has an obvious therapeutic effect on acute lactation mastitis.