Usually saline has many effects on the human body, the most common role is to rehydrate, for dehydrated patients such as acute gastroenteritis and the increase in the number of vomiting, or diarrhea increased the number of supplemental saline have a certain effect of replenishing body fluids. Supplementary saline also has a certain effect of disinfection and sterilization on the human body, for example, when an infection occurs, timely supplementation of saline has a certain anti-inflammatory and sterilizing effect on the human body. Saline supplementation is effective in maintaining acid-base balance and intracellular fluid balance, and appropriate rehydration in patients with hypertonicity and coma has a good coordination and balancing effect on maintaining the osmotic pressure inside and outside the plasma.