The range of normal red blood cells is 4-5.5 million/ml for adult males and 3.5-5 million/ml for adult females. If the number of red blood cells exceeds the normal range, it is an increase in red blood cells. If there is a mild increase in red blood cells, for example, below 6 million/ml, there is no significant effect on the body and all that is needed is to drink more water and exercise regularly. If the number of red blood cells is severely increased, more than 10 million/ml, the viscosity of the blood will increase 6-8 times more than normal and needs to be dealt with immediately. The most effective way is to apply a blood cell separator to separate out the excessive red blood cells in the blood, and at the same time transfuse back to an equal amount of saline or plasma. It is also possible to take the method of venous bloodletting, bleeding 200-400ml every 2 days until the number of red blood cells is below 6 million/ml, while returning to the equivalent amount of saline, and finally, chemical drugs such as hydroxyurea can be applied to inhibit the production of red blood cells and reduce the number of red blood cells.