Six qi circle diagram can be divided into subjective circle diagram and objective circle diagram.Huangdi Neijing was the first book which recorded the five yun six qi theory,but the contents were very difficult to understand.The author invented the six qi circle diagram in order to understand and use the basic knowledge of six qi.It was easier to know the six qis situation of every year,every step by using the two circle diagram.It is easy to calculate and predict the normal and abnormal climatic change.