The digestive and absorbing functions of the stomach, the spleen and the large and small intestines play a key role in the production of body fluid. Body fluid comes from food, especially water and liquid diet. The production of body fluid comes through a series of physiological activities, including the functions of the stomach to receive and digest, the functions of the spleen to transport, transform and transmit, the functions of the small intestine to receive and digest, and the functions of the large intestine to transmit and change. Different viscera may exert different effect on the water taken into the body. So the metabolism of body fluid is accomplished under the coordination of different viscera.