Peritonitis is an infectious disease that is caused by the presence of infection in the abdominal cavity from various causes that irritates the abdominal wall with significant pain, which may be accompanied by rebound pain and muscle tension. Peritonitis can be divided into limited peritonitis and diffuse peritonitis, which refers to the extent of the infection in the abdominal cavity. There are many causes of peritonitis, such as acute appendicitis, acute cholecystitis, gastric perforation, duodenal perforation, malignant tumor perforation, or intestinal torsion or intussusception. After the discovery of peritonitis, it is necessary to go to the hospital as soon as possible to improve the relevant examinations, identify the cause and carry out treatment. If it is caused by an infection, anti-inflammatory treatment is needed, and if necessary, the tissue causing the infection should be removed. If it is caused by tumor, we need to actively improve the relevant examination and perform radical resection of the tumor, followed by chemotherapy and targeted drug therapy.