Objective & Method : By investigating physiological function of tri-energizer, symptoms, and organ coordination, we obtained following conclusion. Tri-energizer is the membrane structure that surrounds the five visceral organs and six hollow organs, and filled with fluid. Tri-energizer acts as the passage for the flow of qi energy. Result & Conclusion : Therefore, dysfunction of the tri-energizer is caused by abnormal evaporation and metabolism. Upper-energizer regulates cardiopulmonary function, middle-energizer regulates spleen and stomach functions, and lower-energizer regulates liver, kidneys, small and large intestines, and bladder functions. Such a functional specialization is possible by receiving the source of qi through the wall wrapping around the internal organs. Tri-energizer represents the exterior and interior relationship by acting as the membrane structure supporting the five visceral organs and six hollow organs and at the same time, as the pericardium surrounding the heart.