The purpose of this paper is to introduce WuKunlun’s experience in the treatment of malignant tumors with Wu’s Xiaoliu Powder. It is considered that the basic pathogenesis of malignant tumor is the deficiency of vital qi and chronic and repeated obstruction of turbid phlegm, toxin and blood stasis. When treating the disease, the methods such as strengthening the spleen to supplement qi, strengthening healthy qi to consolidate constitution, clear away heat to eliminate dampness, and removing toxin to eliminate accumulation are used, and Wu’s Xiaoliu Powder is prescribed for the disease. Also two proven cases are presented.