Review of historical literature showed that the understanding of the indicated disease location of

Modified FuMai Decoction

（复脉汤加减方） has evolved from the upper

jiao

（焦） to the middle and lower

jiao

. Initially， it is used for the treatment of yin deficiency of both yin and yang in the upper jiao， changes to supplement stomach and produce fluids in the middle jiao， and is used to protect yin， clear the pathogens， conslidate yin and subdue yang so as to store the true yin of lower jiao. The unchanging principle of

Fumai Decoction

modifications is nourishing yin， while the changing aspects are determining the secondary treatment methods based on disease location of sanjiao， concomitant disease natures， internal injury or external contraction， warm disease or cold damage， thereby choosing the corresponding added or subtracted herbs， and providing reference for the application of classical formulas.