The article summarized professor Li Yan’s clinical experience in treating bladder cancer by elimination of pathogens through purgation and diuresis. The occurrence of bladder cancer was due to the insufficiency of the spleen and kidney, while dampness in Sanjiao was an important pathological mechanism. Therefore, tonifying deficiency was mainly to strengthen the spleen and kidney, while the way to eliminating dampness pathogenic factors was purgation and diuresis, adjusting qi activity of Sanjiao. Giving consideration on both strengthening the body resistance and eliminating pathogenic factors could improve the clinical efficacy, and one proven case was presented.