A normal increase in lymphocyte percentage occurs in childhood and generally decreases to normal adult levels by the age of 4-6 years. Excluding such cases, if the examination shows a high lymphocyte percentage, certain diseases may exist, and the first step is to go to the hospital to clarify whether the lymphocyte count is an absolute or relative increase: i. Relative increase: The relative increase in lymphocyte ratio is mainly due to a decrease in the number of other cells for certain reasons, but the absolute value of lymphocytes is not increased, such as aplastic anemia, granulocytopenia, granulocyte deficiency, acute hematopoietic arrest, after organ transplantation, tumor and malignant hematological disease after chemotherapy in the bone marrow suppression period, etc. The specific cause should be identified at the hospital and treated for the cause. Second, the absolute increase: 1, infectious diseases: mostly infected with viruses, patients may appear fever, nasal congestion, runny nose, cough, sore throat and other symptoms of upper respiratory tract infection, generally can be found in the following diseases such as measles, rubella, chickenpox, viral hepatitis, mumps, etc., can also be seen in tuberculosis, syphilis, brucellosis, rickettsial infection, etc.. The presence of these diseases leads to a decrease in the body’s immunity and the body needs to produce more lymphocytes to defend itself against the disease. It is recommended to go to the hospital for standardized antiviral treatment, such as taking antibiotics and other antibacterial or virus multiplication control drugs, and if the body produces a high fever reaction, antipyretic drugs are required, and the percentage of lymphocytes will generally return to normal levels after cure; 2. Recovery period of acute infectious diseases: common acute infectious diseases in clinical practice include acute viral hepatitis, influenza, epidemic B encephalitis, rabies, hand, foot and mouth disease If patients do not take medication as prescribed by the doctor or take some allergic drugs that can cause lymphocyte elevation, they need to take medication strictly according to the doctor’s prescription; 3. The percentage of lymphocytes will show a progressive increase, and the white blood cell count will also increase, so the diagnosis requires bone marrow aspiration and symptomatic treatment according to the doctor’s instruction; 4.