At present，traditional Chinese medicine mainly discusses the pathogenesis of malignant tumor from “phlegm，deficiency and blood stasis”，ignoring the essential characteristics of cancer.Based on the concept and pathological understanding of malignant tumor in modern medicine，this paper，combined with the theoretical system，believes that the essence of malignant tumor is the accumulation of essence，and the core pathogenesis of malignant tumor includes 2 aspects:First，the functional pathogenesis of malignant tumor is the accumulation of essence，erosion and growth，blood vessel congestion，functional impairment，and the consumption of righteous qi.Second，the material pathogenesis of malignant tumor is excessive “vital qi ”，and the sensitivity of the production of malignant tumor substances，partial sensitivity of qi and blood.