It is not scientific to determine whether a cough has become pneumonia by how long it has been present, but attention should also be paid to clarifying it in conjunction with other manifestations of itself and the corresponding necessary tests. If the patient has a chronic cough for more than two weeks, possible chronic infectious and non-infectious factors need to be considered. Infectious factors commonly include mycoplasma, chlamydia and Mycobacterium tuberculosis, and at this time the patient presents with an irritating long-term cough accompanied by symptoms of coughing up sputum or even hemoptysis, a persistent rise in body temperature, but with symptoms of depression and loss of appetite, the presence of pneumonia needs to be considered, and the presence of inflammatory lesions seen by lung CT Inflammatory lesions in both lungs can be clearly diagnosed. Non-infectious factors are mainly due to the invasion of allergens, and cough variant asthma, only appearing simple persistent irritating cough without any other symptoms, the patient’s general condition is good, and the CT examination of both lungs is normal, and doing the lung function test has decreased, such as a positive bronchodilator test can be diagnosed as asthma rather than pneumonia.