Objective : In order to find the decision system in differentiation of syndromes and treatments, I paid attention to divination by Achillea sibireca. Method : I pulled out the elements of differentiation of syndromes and treatments in Zhong yi nei ke xue(中醫內科學), Uihagipmun ·Sanghan(醫學入門·傷寒), Donguibogam ·Japbyeong(東醫寶 鑑·雜病) and compared them with the horoscope in The Book of Changes(周易) from the relativity of both eight principles(八綱) etc and subdivision in the entity of the cosmos (太極內分化). Result : From this viewpoint, the decision system that has relative references in differentiation of syndromes & treatments on cold diseases(傷寒病) and complexed diseases(雜病) by eight principles etc can be compared with the decision system in divination by Achillea sibireca that the entity of the cosmos(太極) gradually can be breakdown into the positive and negative(陰陽), the positive and negative can be breakdown into four phases(四象), four phases can be breakdown into eight signs of divination(八卦), eight signs of divination can be breakdown into 64 divination signs(64卦). Conclusion : I had found that differentiation of syndromes and treatments and divination by Achillea sibireca have similarity to each other in side of decision system. Those decision systems for clinical use and telling the future has many relative references and are made of multiple structures. Clinician can easily, exactly distinguish similar syndromes of many another diseases through this way.