The tuberculin skin test is a test to screen for tuberculosis disease. The test is performed by intradermal injection of a pure protein derivative of tuberculin, and the skin test is taken. The test determines whether the body has been infected with Mycobacterium tuberculosis or is being infected by Mycobacterium tuberculosis based on the delayed metaplasia that occurs in the skin.1. Test: A needle is pricked into the skin of the upper arm and a pure protein derivative of tuberculin is injected into it, which forms a circular mound on the skin. The result is usually observed in 48-72 hours. Scratching and rubbing of the skin in this area are forbidden, no water or hormonal drugs should be used, and allergy-prone food should be forbidden. 2. Results viewing: The main focus is on the diameter of the local microscopy, and if no hard nodules or hard nodules of <5mm in diameter appear, the rebellion is set as negative (-); hard nodules of 5-9mm in diameter are generally positive (+); hard nodules of 10-19mm in diameter are moderately positive (++); if the diameter ≥ 20mm, or if blistering, rupture, or lymphangitis occurs, it is a strong positive (++); 3. Judgment of results: If the test result is positive, one possibility is to suggest that the tuberculosis bacillus has been infected, at which time no vaccination is needed. If the test result is negative, then inoculation is recommended. The other possibility is that the body is being infected with TB bacteria, and further confirmation is needed with chest X-ray examination and sputum examination.