To determine whether a child is infected with chlamydia and mycoplasma can be based on symptoms, imaging and laboratory tests. 1. Symptoms: Chlamydia and Mycoplasma infections mainly cause interstitial inflammation of the lungs, and the child mainly manifests a dry cough. Mycoplasma infected children often manifest a persistent, violent dry cough, often with mucous sputum, accompanied by varying degrees of fever, and the lung signs are not obvious. In Chlamydia trachomatis, the child has a paroxysmal, incoherent cough, and Chlamydia pneumoniae has a more insidious onset. 2. Imaging: light signs and X-ray examination obvious change is the characteristics of mycoplasma pneumonia, X-ray can be seen bronchopneumonia, interstitial pneumonitis, pulmonary portal shadow coarsening and other changes, severe cases can be seen pleural effusion. Chlamydia pneumonia is characterized by interstitial pneumonia on imaging. 3. Laboratory tests: mycoplasma and chlamydia antibody test can be done, or take secretions for culture to determine whether the infection of chlamydia and mycoplasma. Mycoplasma pneumonia may develop into refractory pneumonia, which may involve multiple systems and even cause multiple system failure. Chlamydia trachomatis pneumonia can rapidly worsen and even cause death. Therefore, children with suspected chlamydia or mycoplasma infections should go to a regular hospital in time.