As we are now in winter, the number of patients with respiratory tract infections is gradually increasing due to the cold climate, and therefore the number of patients asking about the diagnosis and treatment of pneumonia is also increasing, we would like to discuss the diagnosis and treatment of this common disease. Pneumonia is divided into community-acquired pneumonia and hospital-acquired pneumonia, depending on the mode of acquisition. Community-acquired pneumonia (CAP) is more common in the general population and refers to infectious inflammation of the lung parenchyma (including the alveolar wall, or interstitial lung in the broad sense) that occurs outside the hospital, including pneumonia that develops within an average incubation period after hospital admission due to a pathogenic infection with a definite incubation period. The diagnostic criteria are: 1. new onset of cough, sputum, or aggravation of existing respiratory symptoms with purulent sputum; with or without chest pain; 2. fever; 3. pulmonary solid signs and/or wet oral rales. 4, WBC > 10 × 10 9/L or < 4 × 10 9/L with or without leftward nuclear shift; 5, chest X-ray showing lamellar or patchy infiltrative shadows or interstitial changes, with or without pleural effusion. The clinical diagnosis can be established if any of the above items 1 to 4 plus item 5, and other lung diseases such as tuberculosis and lung tumor are excluded. According to the epidemiological survey, the current pathogenic spectrum of CAP: 1, firstly, bacterial infections, mainly Streptococcus pneumoniae (20-60%), the rest are Haemophilus influenzae, Klebsiella pneumoniae, etc.; 2, followed by atypical pathogens, mainly Mycoplasma pneumoniae (20-30%), Chlamydia pneumoniae, Legionella pneumophila, etc.; 3, multiple infections, i.e. mixed infections of bacteria, viruses or Mycoplasma pneumoniae, etc. infections. Treatment is mainly based on pathogenesis to give targeted treatment, but most patients in the outpatient clinic or admission without a clear pathogenic basis, we often still give empirical treatment first, and advocate the use of antibiotics in combination, commonly used drugs are azithromycin + cefuroxime sodium or ceftriaxone sodium, fluoroquinolones alone or + one or two generations of cephalosporins, clindamycin + two or three major cephalosporins, etc., severe pneumonia is not in this Discuss.