To enrich and develop the theory and practice of TCM etiology， taking “toxin-heat” etiological study of gastric ulcer in active state (GUIAS) as a breakthrough， to establish the research methods of TCM etiology and elucidated the therapeutic mechanism of GUIAS TCM therapy.Methods： By theoretical analyses， experiments， clinical epidemiological investigations， clinical trials of Chinese medicine， we systematically analyzed the role of “toxin-heat” etiological factor in gastric ulcer in active state. Results： Case-control studies revealed that 83.3% out of 581 patients with GUIAS presented a “toxin-heat” syndrome which was only diagnosed in 13.3% of 266 patients with superficial gastritis. Multiple logistic regression analysis further confirmed that “toxin-heat” could lead to helicobacter pylori infection， bile reflux， increase of inflammatory factors and abnormal secretion of gastrointestinal hormone， etc. In a 300-patient-involved clinical trial， syndrome analyses and gastroscopy showed that the effective rate of the treatments was as high as 86.62% and 80.29%， respectively. Besides， this project modified the animal model and its evaluation method， and verified the efficacy of TCM extract and elucidated the underlying biological mechanism. Conclusion： “Toxin-heat” is a common and frequent cause of GUIAS. Treating GUIAS as carbuncle is a new and effective way for GUIAS therapy， which is capable of clearing heat， detoxifying， and eliminating carbuncle while growing muscle.