Recurrent miscarriage refers to two or more consecutive spontaneous miscarriages. The etiology of recurrent miscarriages is complex and no other cause of miscarriage has been identified except chromosomal abnormalities, anatomical abnormalities, endocrine abnormalities, infections, and autoimmunity, etc. It is called homozygous immune heterozygous and can also be called recurrent miscarriage of unknown cause. Currently, active immunotherapy using the patient’s husband or healthy third-party lymphocytes for recurrent miscarriages of unknown cause has achieved good clinical results. In fact, pregnancy is an extremely complex physiological process. Half of the genes carried by the embryo are of paternal origin and the antigens expressed are foreign to the mother. Therefore, from an immunological and transplantation point of view, pregnancy is a semi-identical transplantation process. This particular transplantation phenomenon has been of interest for a long time. With the increasing research, the modern immunological view is that the embryo carrying foreign antigens in normal pregnancy is able to obtain “immune escape” and grow further in the mother until birth because the maternal immune system responds to the recognition of the paternal antigens of the embryo with immune nutrition and immune protection rather than immune This is a specific type of peripheral immune tolerance, i.e. gestational immune tolerance. The mechanisms underlying this state of tolerance are complex and involve the existence of anatomical and immunological barriers between mother and fetus, the immunological properties of embryonic antigens, the expression pattern of human leukocyte antigens on the surface of embryonic trophoblasts, the presence of specific or non-specific immunosuppressive factors in the peripheral blood of the pregnant woman and the balance of Thl, Th2 and Th3 cytokines. The balanced regulation between immune activation and suppression at the maternal-fetal interface plays a crucial role in the growth and development of the embryo and fetus. Various immune factors form a network through organic coordination to achieve a balance in the immune relationship between mother and fetus so that pregnancy can be maintained. If this immune balance is disrupted, the embryo will suffer an immune attack and miscarriage, i.e., homozygous RSA, which is now considered to be an alloimmune disease. In the last 20 years, significant progress has been made in its treatment, and active immunotherapy is currently used. The application of lymphocyte active immunity in the treatment of unexplained recurrent miscarriage is effective, easily accepted by patients, simple, easy to perform and economical with wide clinical application value and good development prospect.