The epidemic diseases have many unique shift laws and can be summarized as six-channel shift

exte- rior-interior shift

Sanjiao shift

twelve-channel shift and Weifen-Qifen-Yingfen-Xuefen（ defense

qi

construction and blood） shift. The six-channel shift of epidemic diseases includes along-channel shift day by day and six-channel exterior-interior shift. The exterior-interior shift includes passing from the exterior to interior

passing to stomach day by day and exterior-interior shift respectively. The Sanjiao shift includes going straight to the middle-jiao（ 中焦） and flowing to Sanjiao and from upper-jiao（ 上焦） to lower-jiao（ 下焦）. The twelve-channel shift is commonly stomach- centered and passing to twelve channels. The Wei-Qi-Ying-Xue shift of epidemic diseases is abnormally passing from Ying-Xue. The location

nature and shift trend of epidemic diseases were introduced in this articles. We should grasp the nature and shift law of epidemic diseases in clinic.