Abstract: Onodera prognostic nutrition index (OPNI) is a simple and effective parameter. It is calculated by serum albumin level and peripheral blood lymphocyte count. Initially, OPNI is used to assess preoperative nutritional status and surgical risk. In recent years, researchers have found that OPNI is related to the prognosis of many tumors. Simple and accurate prognosis evaluation can help to select treatment methods for digestive system malignant tumors, determine the best pre-operative treatment time and operation time, and improve the survival rate of patients with diges-tive system malignant tumors. The authors review the related literatures at home and abroad, and summarize the research advances in the prognostic value of OPNI for malignant tumors of digestive systems.