A positive antinuclear antibody titer of 1:100 may be caused by systemic lupus erythematosus, rheumatoid arthritis, etc. The cause of the positive antinuclear antibody titer of 1:100 should be further clarified, and medication and other treatments should be targeted. Antinuclear antibody is one of the important markers of autoimmune diseases, which should be negative under normal circumstances. The patient’s antinuclear antibody titer of 1:100 is positive, suggesting that the patient may have systemic lupus erythematosus, mixed connective tissue disease, dry syndrome, progressive systemic sclerosis, rheumatoid arthritis and other diseases, and the cause should be clarified by further completing the relevant auxiliary examinations. Common auxiliary tests for autoimmune diseases include blood sedimentation, rheumatoid factor, CRP, autoantibodies, ultrasound, CT, etc. Combined with the auxiliary tests as well as the patient’s clinical manifestations and history of disease, the cause of the 1:100 antinuclear antibody titer should be clarified, and then medication, physiotherapy and other treatments should be carried out to address the cause of the disease. Antinuclear antibody test results should be interpreted by a professional physician, and it is recommended that patients go to the Department of Rheumatology and Immunology of a regular hospital for detailed consultation and treatment as prescribed.