Reduced nicotinamide adenine dinucleotide phosphate （NADPH） oxidase 2 （Nox2） acts as a source of reactive oxygen species， which participates in and influences normal physiological function of human body. Nowadays， many studies have found that Nox2 is related to prognosis of patients， drug resistance and molecular targeted therapy in various malignant tumors， such as acute myeloid leukemia， gastric cancer， colorectal cancer， ovarian cancer， lung cancer and esophageal cancer. What's more， it may be a novel biomarker and a potential therapeutic target for malignant tumors.