Fluorouracil is a chemotherapeutic drug, which is the basic drug for colorectal cancer chemotherapy and belongs to the anti-metabolic class of chemotherapeutic drugs. The main mechanism of action of fluorouracil is that after entering the body, the metabolites of the drug can inhibit adenylate synthase and thus affect the synthesis of DNA in tumor cells to achieve the purpose of anti-tumor. In addition to colorectal cancer, fluorouracil can also be used in the treatment of other gastrointestinal malignancies, such as gastric cancer and pancreatic cancer. In addition, it can also be applied in the treatment of lung cancer, breast cancer and other malignant tumors. In addition to common adverse reactions such as gastrointestinal reactions and bone marrow suppression, mucositis may also occur after the clinical application of fluorouracil, and some patients may experience skin pigmentation and heart damage in patients with underlying diseases such as heart disease.