Chemotherapeutic drugs are cytotoxic and kill cells that proliferate and differentiate more rapidly. Unlike targeted drugs, chemotherapeutic drugs cannot discriminate between tumor cells and normal cells. Therefore, chemotherapeutic drugs also have a certain killing effect on normal cells, and the killing effect on normal cells that proliferate and differentiate quickly will be greater, because white blood cells belong to normal cells that proliferate and differentiate quickly. Therefore, chemotherapeutic drugs kill tumor cells, but also have a certain damage to the same fast-proliferating and differentiating white blood cells, resulting in a decrease in white blood cells after chemotherapy. Lowering of white blood cells after chemotherapy will produce a series of adverse effects on human body, therefore, after chemotherapy, it is necessary to regularly review the changes of white blood cells, and when it is found that white blood cells are lower, it is necessary to give drugs to raise white blood cells in time to ensure that chemotherapy can be carried out smoothly, effectively and safely.