Syndrome differentiation of zang-fu organs is a dialectical method to identify the disease location of zang-fu organs and the changes of yin and yang, qi and blood, deficiency and excess, cold and heat according to their physiological functions and pathological characteristics, so as to provide basis for treatment.

Heart, liver, spleen, lung and kidney are the five internal organs, characterized by parenchymal organs, and their main functions are to transform and store qi and blood, essence and body fluid. Small intestine, gallbladder, stomach, large intestine, bladder and triple energizer are six fu organs, which are characterized by hollow organs, and their main functions are to receive and decompose Shui Gu, transport and excrete dregs. As Su Wen's Theory of Five Zang-organs said: "The so-called five zang-organs are full of essence but not diarrhea, so they are not real; Those who have six internal organs pass on chemicals without hiding them, so they can't be full. "

In addition, the brain, marrow, bone, pulse, gallbladder and daughter cells are called strange and constant fu-organs, and "strange" means different, while "constant" means constant. Because it is similar to fu-organs and has the same function as viscera, it has its particularity. Among them, gallbladder is one of the six fu-organs, because it has the property of "purging without hiding" in general fu-organs, but the bile it excretes is not dregs, but refined juice, which is different from general fu-organs, so it belongs to "extraordinary fu-organs"