Hepatocellular carcinoma platelet 500 may be due to malignant tumor secondary to thrombocytosis. Thrombocytosis often occurs in many kinds of malignant tumors, such as lung cancer, esophageal cancer, breast cancer, gastric cancer, liver cancer, pancreatic cancer and so on. Thrombocytosis can occur in 30%~40% of tumor patients, resulting in hypercoagulable state of blood, easy to thrombosis, and in serious cases, disseminated intravascular coagulation can occur, which is life-threatening. In severe cases, disseminated intravascular coagulation may occur, which may be life-threatening. Chemotherapy increases the content of fibrinogen and shortens the prothrombin time, which exacerbates hypercoagulability of blood. If liver cancer combined with thrombocythemia is suspected or diagnosed, it is recommended to go to a regular hospital to evaluate the condition and follow the doctor’s instructions for treatment, so as to avoid delaying the condition.