The most common causes of high total red blood cell count include the following: i. Relative erythrocytosis, due to dehydration or burns resulting in blood concentration. Second, secondary erythrocytosis, mainly seen in chronic hypoxic diseases, such as long-term residence in highland areas, with congenital heart disease, chronic obstructive pulmonary disease, sleep apnea syndrome and various malignancies such as kidney tumors. Third, true erythrocytosis, this disease is the red blood cell hematopoiesis out of control, overcapacity caused by the increase in red blood cells, there is no other cure except bone marrow transplantation, mainly symptomatic treatment, need to take long-term hydroxyurea tablets or play interferon treatment. The danger of a high total red blood cell count is that it causes an increase in blood viscosity and blood flow stagnation that can easily induce thrombotic diseases, the most common sites of embolism being cerebral infarction and myocardial infarction. If a high total red blood cell count is found in the examination, it is important to find out the cause and treat it early to avoid complications of thrombosis.