Though the clinical observation of 413 cases of epidemic hemorrhagic fever(EHF) by clinical epidemiological method,we have concluded that the main TCM etiological factors of EHF are damp,toxic heat,blood stasis and deficiency, and the determinant pathogenesis of EHF is the integration of interior and exterior pathogenic factors;the syndrome characteristic of EHF is that the cold,heat,deficiency and excess were intermingled,and the moist heat blood stasis syndrome should be given priority to;its major pathological location is initial YANG and triple warmer;so the therapeutic principle should be the integration of cold-warm syndrome and exterior and interior and paying attention to smoothing the triple warmer all the time.