Polycythemia is a blood disease characterized by an increase in red blood cells, hemoglobin, and blood volume. It was first described by Vaquez in 1892. Osler conducted further research on the disease in 1903, so it is also called Vaquez-Osler disease. There are three types: primary, compensatory, and secondary. The primary type is polycythemia vera. It is rare in my country and is generally believed to be caused by hyperplasia of the bone marrow, but its exact cause and pathogenesis are still unclear. Most cases occur between the ages of 35 and 65, with slightly more men than women; the onset is slow and hidden, and symptoms may begin to appear after several years. In some cases, there is no feeling and it is discovered accidentally during a blood test.