The incidence of Crohn disease is on rise year by year in China, and there are still difficulties for the diagnosis and treatment. The diagnosis of Crohn disease is lack of specific markers, and can′t be made unless the other intestinal diseases were excluded. The definite diagnosis depends on comprehensive analysis and follow-up. To transfer the disease to remission stage for definitive surgery, medical treatment or staged surgery would be adopted to control active lesions. This article aims at offering useful guidance for this disease by summarizing the experience and lessons of diagnosis and treatment on one case of active complex Crohn disease.