Anti-phospholipid antibodies (APLA) refer to antibodies that react with different phospholipid components in the body. The two main types of antibodies used in clinical testing so far are lupusanti-coagulant (LAC) and anti-cardiolipin (AcL) antibodies. In recent years, anti-phosphatidylserine antibodies and anti-phosphatidic acid antibodies have also been found. LAC is a kind of immunoglobulin, and its immune activity is mainly in IgG. The clinical tests to measure LAC are activated partial thromboplastin time (APTT), prothrombin time (CPT), snake venom time, and white clay clotting time, etc. When the measured time is prolonged and not corrected by normal plasma, it indicates the presence of LAC. LAC has the highest positive rate in SLE, but idiopathic thrombocytopenic purpura, true erythrocytosis, streptococcal infection LAC is also positive in patients with idiopathic thrombocytopenic purpura, true erythrocytosis, streptococcal infection, malignancy, hepatitis, and neuropathy on phenothiazines. 2, AcL antibody Wassermann in 1907 established the syphilis standard test (STS) is the earliest test to determine the AcL antibody. It uses the liver leachate of congenital syphilis fetuses as the antigen, and is determined by the complement binding test, which actually contains cardiolipin in the antigen extracted from fetal liver. Later, it was changed to use cardiolipin, the active component of bovine myocardial ethanol leachate, as STS. AcL antibodies are positive in 30% to 40% of SLE patients and up to 80% in SLE with reticulocytosis. acL antibodies can also be found in a variety of diseases such as thrombocytopenic purpura, hemolytic anemia, Lyme disease, Hashimoto’s thyroiditis, and tumors. APLA can be classified into IgG, IgM and IgA types. The proportion of their types varies among reports, but most scholars prove that IgG type APLA occupies a prominent position with a high positive rate and the strongest clinical relevance, and it may be more predictive and specific for the appearance of thrombosis, thrombocytopenia, and habitual abortion. It has also been suggested that IgM-type ACL antibodies may be more closely associated with certain clinical manifestations, such as habitual abortion, and stillbirth.