The suitable temperature for stock blood preservation is 4~6℃ and the suitable time is 2~3 weeks. 1. Stock blood refers to the whole blood that is collected without any alteration and kept in reserve, which is mainly used for replenishing blood volume and correcting anemia in clinic, and is suitable for large blood loss caused by various reasons. Stock blood is kept in the refrigerator at 4~6℃ with the validity period of 2~3 weeks, and its components are mainly red blood cells and plasma proteins. 2. The prolongation of storage time of stock blood will lead to an increase in the destruction of components such as white blood cells, platelets and prothrombin, etc. Due to the destruction of cells, the intracellular potassium ions spill over, and the concentration of potassium ions in the blood will increase. Therefore, when a large amount of stock blood is imported, it can cause the serum potassium concentration to exceed the normal range, thus leading to hyperkalemia. 3. If symptoms of hyperkalemia such as panic, chest tightness and slow heart rate occur after large amount of stock blood is imported, it is recommended that potassium-excreting diuretics such as furosemide and torasemide should be applied in time under the guidance of doctors for treatment.