The invention relates to a rehydration method of piglet diarrhea rehydration salts. Piglets are divided into two day age groups which are respectively supplemented with the rehydration salts, the first day age piglets are supplemented with a first rehydration salt in an intraperitoneal injection manner, and the second day age piglets are supplemented with a second rehydration salt in a drenching or free water drinking manner. The first day age group is piglets of seven or below day ages, and the second day age group is piglets of above seven ages. In the invention, the piglets are divided into two day age groups according to the body growth differences of the piglets of different day agents and are supplemented with different rehydration salts to ensure the rehydration effect, so the rehydration method of piglet diarrhea rehydration salts decreases the labor operating strength and increases the maneuverability of the rehydration method. The rehydration method of piglet diarrhea rehydration salts has the effects of piglet body electrolyte and acid-base balance maintenance, energy supplementation, stress resistance, anti-inflammation and vomiting prevention.