Professor Wang Jialin is a nationally renowned expert in traditional Chinese medicine. He has accumulated rich clinical experience in the treatment of ulcerative colitis and other difficult diseases for more than 70 years. This paper summarized professor Wang Jialin's experience in the treatment of ulcerative colitis with Baitouweng decoction, the similarities and differences between professor Wang Jialin's modified Baitouweng decoction and that recorded in ,Treatise on Cold Pathogenic Disease, were compared and analyzed, then made a more detailed discussion on how to apply the 11 kinds of modified methods of Wang Jialin's Baitouweng decoction. Furthermore, this paper shows the characteristic of medicine that pay attention to the balance of Yin and Yang, and lists the typical cases. The purpose of this paper is that emphasize a positive role in inheriting the experience and academic thoughts of famous veteran doctor and improving the clinical efficacy of ulcerative colitis.