Sputum culture is performed in patients with pulmonary tuberculosis to confirm the diagnosis and the effectiveness of drug therapy, including whether the patient is in the infectious phase. Sputum is isolated for Mycobacterium tuberculosis, and culture of Mycobacterium tuberculosis is performed; sputum specimens are liquefied and homogenized before quantitative culture is performed, and any antibacterial drugs are stopped for more than two weeks. When collecting sputum, care should be taken to prevent contamination by colonized bacteria in the oral cavity, and sputum should be obtained directly without touching the oral mucosal wall if possible. Since the morning sputum is relatively abundant, it is possible to take morning sputum from the deep bronchial tubes coughed up by continuous coughing. If the culture of Mycobacterium tuberculosis is positive, the diagnosis of tuberculosis is established, and drug sensitivity tests can be done at the same time to select sensitive anti-tuberculosis drugs for the best therapeutic effect.