Abstract: Tumor differentiation and treatment by TCM is discussed in this paper and the academic thought of "cancerous toxin" has been raised based on the clinical practice of determining etiologic factors based on differentiation and treating tumor by ways of dispelling poison， detoxifying and counteracting toxic substances. Tumor is considered to be the result of the disorder of qi transformation of zang-fu organs， with phlegm and toxicity stasis as the core of the pathogenesis. Thus， syndrome and disease differentiation should be complementary and the development of evil qi and vital qi， the connection between tumor and the diseases should be fully considered. Detoxifying and counteracting toxic substances should be adapted to the patients' situation and the pathological features should be judged by the site of the tumor. Compound methods and complex prescription are proposed as the vital method to treat tumor and the key points of using medicines are mentioned in this paper. For example， relieving symptoms are of great importance and the recurrence and metastasis of tumor should be stopped and the most important thing is to nourish the vital qi.