The hand belongs to the end of the human body’s circulation, where there are a large number of tiny arterial and venous connections and capillaries, the most affected by the temperature of the arterial and venous short circuits, but also exists in the fingers and feet, arterial and venous short circuits are mainly regulated by the temperature of the hand in a hot environment, the temperature becomes higher, while affecting the pathway, the amount of openings of this pathway will be increased, the increase in the same time, it will accelerate the flow of blood, and the stagnant blood in the endings. If the temperature decreases, the opposite will be closed, the blood flow will be slowed down, and the local pooling of blood will be reduced, which is a normal physiological phenomenon, without special concern. Local arterial and venous short-circuit opening increases, capillary filling pressure will increase, in the local tissue fluid production will also increase, is also one of the causes of hand swelling, can be relieved by elevating the limb or local cooling.