Through the comparative study of relevant literature, this paper analyzes the physiological function and pathological performance of the four pagodas on the human body, and studies the circulation regularity, the physiological and pathological performance and the main disease therapeutic fields of meridians and sinews. It is concluded that each meridian has the corresponding pagoda attribute while as the main body of the meridian and sinew. The four pagodas syndrome differentiation is the basic syndrome differentiation method of the diagnosis and treatment system of Dai medicine; the meridian sinew syndrome differentiation is the characteristic syndrome differentiation method of Dai medicine applied to external treatment; the four pagodas disease contains the meridian sinew disease; the four pagodas syndrome differentiation guides the meridian sinew syndrome differentiation; and the meridian sinew syndrome differentiation improves the clinical syndrome differentiation efficiency. The above indicates that the four pagodas theory and the meridian sinew theory are not used separately, but are widely and deeply combined in clinical practice.