Anti-smooth muscle antibodies are autoantibodies that use human smooth muscle tissue as the antigen and have no organ or species specificity, and can be divided into two types: IgG and IgM. Currently, indirect immunofluorescence is commonly used in clinical practice to detect anti-smooth muscle antibodies as a marker for detecting type I autoimmune hepatitis, with a high positive detection rate. Positive anti-smooth muscle antibodies are mainly seen in autoimmune hepatitis, primary biliary cirrhosis, acute viral hepatitis, chronic active hepatitis and other autoimmune diseases, as well as inflammatory bowel disease and infections, such as mycoplasma pneumonia, infectious mononucleosis, leprosy, etc. Some elderly people sometimes have anti-smooth muscle antibodies, which can also show positive results. Anti-smooth muscle antibodies are mainly detected by serum, and a positive result can be considered as autoimmune hepatitis first, but it should also be combined with other related tests for a comprehensive diagnosis and differentiation from other diseases, which should be analyzed by clinicians in combination with medical history, symptoms and signs to arrive at an accurate diagnosis.