Patients who are found to have high lymphocytes during routine blood tests in clinical practice generally often have the following causes: i. Viral infections are mostly seen in patients with upper respiratory tract infections, herpes zoster infections, and some bronchial infections. At this time, the high level of lymphocytes in the blood will be caused by the massive multiplication of viruses in the body, which will cause the immune organs of patients such as lymphocytes to increase in content to kill the viruses in the body. Clinically, active antiviral treatment can be used to kill the virus in the body and induce the lymphocytes to return to normal. Second, lymphoma. Patients with lymphoma can have a significant increase in lymphocytes through blood tests due to the proliferation of lymphoid tissue in the body. At this time, patients need to undergo pathological section examination to clarify the type of lymphoma and the suitable chemotherapy regimen. Through active chemotherapy treatment, some patients with lymphoma can achieve better treatment results.