The most important function of sodium chloride injection is to regulate the water and electrolyte balance in the body as well as to replenish electrolytes. Because sodium chloride is an electrolyte replenishing drug, sodium and chloride ions are relatively important electrolytes in the body, mainly present in the extracellular fluid, and play a relatively important role in maintaining the normal plasma and extracellular fluid osmolality. The concentration of sodium in normal human blood is 135-145 mmol/L, accounting for 92% of plasma cations and 90% of total osmotic pressure, so sodium chloride plays a very important role in maintaining the balance of osmotic pressure in the body. Once the lack of chloride ions and sodium ions in the body is very dangerous, so sodium chloride injection can play a role in balancing body fluids. In addition, many drugs also need to be dissolved in sodium chloride injection in order to be injected intramuscularly, or treated intravenously by IV drip, so sodium chloride injection is very versatile.