Traditional Chinese medical diagnostics includes 2 parts: the method of diagnosis and the determination of treatment based on the differentiation of symptoms and signs. The method of diagnosis is composed of inspection, auscultation and olfaction, inquiry and palpation. Inspection is the method to see the patient’s expressions, complexion, physique, posture, tongue and the fur on it and the color of secretion and excrement in order to know the situation on the internal organs. Expressions ans the tongue are the most important. Auscultation and olfaction are the method to listen to the patient’s sounds to smell the ordor of his/her breathe and discharge. The changes of his/her breathe and discharge can tell the illness. Inquiry is the method to inquire the whole information. As to palpation, pulse feeling is the chief item. The eight principles are: yin and yang, exterior and interior, cold and heat, deficiency and excess. They are analyzed from the data obtained from the 4 methods of diagnosis. Yin and yang syndromes are the general principles of the eight.