Abstract: China has a very high incidence of gastric cancer. Chinese medicine has advantages in the treating of gastric cancer. Professor Zhou Zhong-yin， awarded National Chinese Medical Science Master， has put forward the theory of cancerous toxin pathogenesis theory based on his long-term clinical experience. Better effect of the treatment of gastric cancer has been confirmed by the application of cancerous toxin pathogenesis theory on gastric cancer patients. Cancerous toxin remaining in the stomach is the key pathogenesis of gastric cancer. Cancerous toxin always intermingled with phlegm turbidity， blood stasis， damp turbidity and toxic heat is very common in the patients with gastric cancer. So the principle and treatment of gastric cancer is the combination of anti-cancer while removing toxic material and other therapeutic principle， such as regulating qi and harmonizing stomach， clearing heat and promoting diuresis， promoting blood circulation to remove blood stasis， reducing phlegm and resolving masses and reinforcing deficiency.