This paper explores the origin of "lung governing skin and hair"theory and its modern medical implication. The author holds that Qi-deficiency constitution is the common predisposition of pulmonary system diseases

based on epidemiology investigation of constitution distribution and clinical counter-evidence aspects. And the paper analyzes the inner relationship between "lung governing skin and hair"and qi-deficiency constitution

based on "lung governing skin and hair"theory

using "defensive-Qi united with liquid"theory as a bridge. Finally

it rises that

"defensive-Qi and liquid dysdiffusion"is the key process of Qi-deficiency constitution characteristic.