Gastrointestinal mesenchymal tumor (GIST) is a disease that has received increasing attention from scholars at home and abroad in recent years. It can occur throughout the gastrointestinal tract from the esophagus to the anus, mostly in the stomach and small intestine, but rarely in the rectum, accounting for 0.11% of rectal malignancies. Since there are still some differences in the diagnostic criteria of benign and malignant GIST, and rectal mesenchymal tumor involves the question of whether to preserve anus or not, which often brings difficulties in clinical treatment. GIST is a type of non-epithelial, non-myogenic, non-neurogenic and non-lymphoid tumor of the gastrointestinal tract, consisting of spindle-type and epithelial-like cells and expressing CD117 protein, which is often misdiagnosed as flat muscle tumor or neurogenic tumor in the past, with the stomach as the preferred site, accounting for about 60%-70% of cases, and the rectum is rare. There are only small samples of cases reported at home and abroad. Rectal mesenchymal tumors are usually found in middle-aged and elderly men, with no specific clinical manifestations, common symptoms include change in stool habit, perineal discomfort and obstruction, and blood in the stool is rare. CT and MRI examinations can help to understand the relationship between the mass and the surrounding structures and help to choose the surgical procedure. Preoperative diagnosis of this disease is difficult to confirm, and preoperative pathological biopsy and smear cytology are often negative, which makes it difficult for the surgeon to choose the surgical approach.