Background Non-Hodgkin Lymphoma (NHL) of the ileum presenting as perforation and peritonitis is a rare disease, derived from intestinal intraepithelial T lymphocytes.The degree of malignancy is extremely high. The pathogenic factors of ileal perforation caused by NHL are not clear yet, Chromosome and immune system abnormalities, which may be related to the NHL, are indistinguishable from other benign and malignant conditions and clinically nonspecific. Case presentation Here,We described an 84 year old male with abdominal pain for four days and aggravating for three hours. The pain was initially considered as gastrointestinal perforation, and was initially located at the upper abdomen area.The persistent insidious pain,and was accompanied by nausea, vomiting and fever. According to the abdominal physical examination, the patient had pain all over his abdomen, rebound pain and muscle tension, and bowel sounds were reduced on auscultation. The abdominal CT scan showed abdominal cavity free gas.We diagnosed the patient with peritonitis due to the perforation of the hollow viscus. We promptly performed exploratory laparotomy.Intraoperative findings,showed perforations in the ileum that were approximately 40 cm from the ileocecal region and had a size of 3～8 mm. Segmental distribution was observed, and the intestinal contents overflowed with purulent moss around the perforation surface. Resection and ileostomy were performed as intervention, and the clinical histopathological examination showed the T-cell lymphoma. Conclusion:Timely emergency surgery is the key to the treatment of the ileal perforation caused by T-cell lymphoma.Resection and ileostomy were performed as intervention, and the subsequent histopathological examination showed T-cell lymphoma. Clinical follow-up was performed, and the patient was advised to go to the oncology department for further chemotherapy.