Biological immunotherapy is the fourth type of treatment for malignant tumors, and DC-CIK biologic cell immunotherapy is the most used biological therapy. DC-CIK biological cell immunotherapy is also known by various names, such as: DC-CIK immune cell therapy, DC-CIK cell immunotherapy, DC-CIK cell therapy, etc. The specific process of bio-immunotherapy is to extract a certain volume of the patient’s own venous blood, after which the cells with the ability to kill are isolated and then cultured in a high standard and strict laboratory to increase their number thousands of times, and then infused back into the patient after reaching a sufficient number to kill the tumor cells and improve the immunity. Fan Kaixi, Department of Medical Oncology, Affiliated Hospital of Shandong Academy of Medical Sciences At present, DC-CIK biological cell therapy is technically mature and has been widely used in Europe, America and many hospitals in China, with excellent results and many patients benefited from it. Bioimmunotherapy can enhance the immune ability of tumor patients’ organism and remove the tumor cells in patients’ body, thus playing the role of controlling metastasis recurrence. Bioimmunotherapy can be applied to the treatment of many kinds of malignant tumors at different stages. It is effective for malignant melanoma, kidney cancer, lung cancer, esophageal cancer, gastric cancer, pancreatic cancer, liver cancer, gallbladder cancer, intestinal cancer, breast cancer, cervical cancer, ovarian cancer, glioma, prostate cancer, bladder cancer, leukemia, lymphoma (except T-cell lymphoma), multiple myeloma, soft tissue sarcoma, etc. In clinical application, it is found that biological therapy can slow down the growth of tumors, stabilize or shrink the masses, or even disappear, and we have records of such good results; it can improve patients’ conditions, improve their quality of life, and enable long-term survival. Biological therapy can be applied alone or in combination with other treatments, and the combination is more effective.