Through the theoretical study on Sa-sang constitutional medicine from a evolutionary point of view, the result was obtained as follows. 1. The system of Sa-Sim-Sin-Mul(事心身物) in Sa-sang constitutional medicine is similar to the theory of evolution of Teilhard de Chardin. 2. The concept of Yin and Yang in Sa-sang constitutional medicine can be set up by the demand and necessity in the progress of evolution and the time of the differentiation of functions. 3. The Sung-Jung(性情) of each Sa-sang constitution can be explained as the strategy and form for survival. 4. The theory of physiology, pathology and therapy in Sa-sang constitutional medicine can be hypothesized by the evolutionary standards which are related with the thermo-metabolism and hematopoietic-immune system.