Peritoneal mesothelioma is a tumor originating from the epithelial and mesothelial tissues of the peritoneum and is rarely seen clinically. Pathologically, they can be classified as adenomatoid mesothelioma, cystic mesothelioma, and malignant mesothelioma. Peritoneal mesothelioma is a tumor originating from the epithelial and mesothelial tissues of the peritoneum and is rarely seen clinically. Pathologically, they can be divided into adenomatoid mesothelioma, cystic mesothelioma, and malignant mesothelioma. The first two are benign tumors. Cystic mesothelioma is most commonly seen in women and has an unknown etiology. It is usually found in the pelvic cavity or around the adnexa as a single or multiple cystic masses; patients are often seen for abdominal masses. Malignant peritoneal mesothelioma (PMM) accounts for about 30% of malignant mesothelioma; its occurrence is also closely related to asbestos exposure, with about 5% of patients having a history of exposure; asbestos fibers are ingested orally and translocate through the intestinal wall to the peritoneum to cause disease or metastasize from the pleura. The incubation period of the disease can be as long as 25~40 years from the time of exposure to asbestos to the time of diagnosis. However, only one of the 161 cases of PMM reported in 20 papers from 1951 to 1993 in China had a history of asbestos exposure. Eight of the 47 cases of mesothelioma reported by Zhou Yakang et al. with malignant peritoneal mesothelioma, as well as the two cases collected by the author, had a history of asbestos exposure. The incidence of PMM in people without a history of asbestos exposure is about 1 person per 1 million people per year, which may be related to certain viral infections and genetic factors. PMM has been reported in a patient with PMM who was exposed to colloidal thorium dioxide (Thorotrast) more than 40 years ago, and it often occurs in men over 40 years of age. The tumor can directly invade the abdominal and pelvic organs; 50% to 70% of patients have lymphatic and/or hematogenous metastases to the liver, kidneys, adrenal glands, lungs, and bones. The clinical manifestation of PMM lacks specificity and may include abdominal pain, constipation, abdominal distension, weight loss and other intestinal obstruction manifestations. Physical examination may reveal ascites or peritoneal masses, etc. The ascites is exudate and some of it is bloody. It is easily misdiagnosed as tuberculous peritonitis, recurrent spontaneous peritonitis, inflammation of the mesentery or peritoneal metastatic cancer. A significant increase in ascites hyaluronic acid greater than 0.8 g/L is seen only in PMM. ascites exfoliative cell examination is also of some value, but the results are often difficult to determine. Elevated serum glycoconjugate antigen – 125 (CA125) can help diagnose this disease. Clinical staging: Butchart et al. divided PMM into 4 stages: stage I, tumor confined to peritoneum; stage II, tumor invading intra-abdominal lymph nodes; stage III, tumor metastasis to extra-abdominal lymph nodes; stage IV, distant hematogenous metastasis. There is no effective and standardized treatment plan for PMM so far. The prognosis is very poor, with a median survival of 1 year after diagnosis and less than 20% surviving more than 2 years. Death is mainly due to malignancy or intestinal obstruction, and the cause of death is rarely related to distant metastases from the tumor.