Abstract： Tiangan Formulas were created by CHEN Wuze and first recorded in the San Yin Ji Yi Bing Zheng Fang Lun (Treatise on Diseases， Patterns， and Formulas Related to the Unification of the Three Etiologies). They refer to 10 formulas guided by the theory of five circuits and six qi and based on the law of harmful hyperactivity and responding inhibition of the five phases， using the four qi and five flavors of medicinals to treat and prevent diseases and syndromes that have already appeared or may appear in the human body due to excessive or insufficient year evolutive phase. Their formulation follows 4 principles， namely the harmony of qi and flavors， the dynamic balance of yin and yang， supplement/drianage for bitter-desire of the five viscera， and the five-phases restriction and generation； there are different principles of formulation to deal with excessive or insufficient year evolutive phase. The purpose of treatment is to correct bias in human body through medicinals with bias nature and restore the dynamic balance of human qi transformation. When applying such treatment，attention should be paid to identifying circuits and qi， observing constitutions， and distinguishing diseases and syndromes. The scope of application includes disease prevention and treatment for diseases caused by excessive or insufficient year evolutive phase.