Gastrointestinal mesenchymal tumor 5.5cm is likely to be malignant. Gastrointestinal mesenchymal tumors are judged to be malignant according to the tumor size and split image: intragastric tumors >5.5cm or small intestinal tumors >4cm are mostly malignant. Secondly, per high magnification field of view, tumors in the stomach with more than 5 schizonts or tumors in the small intestine with more than 1 schizonts are mostly malignant. So gastrointestinal mesenchymal tumor 5.5cm mostly belongs to malignant tumors, and it is generally clinically selected by the way of surgical treatment, and then according to the type of pathology and the results of genetic testing, to determine whether to treat with targeted drugs, such as imatinib. Gastrointestinal mesenchymal tumor requires regular follow-up in the hospital to dynamically observe the patient’s condition.