Allogenic hematopoietic stem cell transplantation is the most effective and fundamental method to cure malignant blood diseases at present.Gastrointestinal graft-versus-host disease is a common complication after transplantation.It requires early diagnosis and treatment, because of its high incidence rate, severe clinical manifestations, complex gastrointestinal manifestations and poor prognosis.In clinical practice, it is often differentiated from causes such as infection and chemotherapy drugs.Endoscopic manifestations and pathological findings obtained through endoscopy are important evidence for the diagnosis of gastrointestinal graft-versus-host disease, especially for gastrointestinal graft-versus-host disease that is difficult to be diagnosed clinically.This article reviews the significance, manifestations, biopsy sites, and pathological features of endoscopy in the diagnosis of gastrointestinal graft-versus-host disease.