The invention relates to a method for preparing positive serum of an autoimmune antigen. The method comprises the following sequentially-executed steps: (1) repeatedly immunizing a healthy animal with an autoimmune antigen, drawing blood from the healthy animal before every immunization, so as to assay an OD (Optical Density) value, ending immunization after the OD value is stable, and drawing blood, so as to obtain antiserum; (2) carrying out affinity purification on the antiserum obtained in the step (1), so as to obtain an IgG (Immunoglobulin G) antibody; (3) coupling the IgG antibody obtained in the step (2) and a human IgG antibody according to the mass ratio of 1: (1-5), then, separating and purifying, so as to obtain an IgG-IgG connective concentrated solution, and diluting the IgG-IgG connective concentrated solution until the concentration is 0.5-1 microgram per milliliter, thereby obtaining the positive serum. The method disclosed by the invention can be applied to the batch preparation of positive serums of various autoimmune antigens and is simple and easy.