The most accurate test for tuberculosis infection in children is sputum culture, in which the presence of Mycobacterium tuberculosis in the sputum is the basis for confirmation of the diagnosis. In addition, tests include tuberculin skin test, T-cell subgroup assay, and chest imaging. It should also be combined with the child’s medical history, whether the child has symptoms such as wasting, low fever, night sweats, hemoptysis, and whether the child has been injected with BCG vaccine. 1. Sputum culture: It is one of the most accurate tests for diagnosing tuberculosis. If a child does not know how to cough up sputum, it can be tested by aspirating sputum from deep in the mouth through a nasogastric tube or aspiration tube early in the morning before the child wakes up and eats. If there is an accompanying airway discharge or severe infection and the trachea has been intubated, the sputum can be aspirated locally and sent for testing. Generally TB culture takes 4-8 weeks, and if TB bacilli are cultured, it proves that TB infection does exist; 2. Tuberculin skin test: Inject a 0.5-1 cm mound intradermally in the middle and lower 1/3 of the child’s forearm, and then observe for 48-72 hours. If the local mound is red, swollen, hard, and >15mm in diameter, or if there are obvious blisters or ruptures, it indicates the presence of tuberculosis infection; 3. T-cell subpopulation assay: check by blood collection. If the T-cell subsets are obviously positive after the test, and all the test values are >6%, it also indicates the possible presence of tuberculosis infection, and the site of tuberculosis infection needs to be actively investigated; 4. Chest imaging: chest X-ray and chest CT can be done. If local tuberculosis balls or cavities are found, along with calcification, the presence of tuberculosis is generally considered.