Abstract: OBJECTIVE To investigate the correlation and clinical characteristics of Mycoplasma pneumoniae and Chlamydia pneumoniae infections in children with asthma. METHODS A total of 1286 cases of children with asthma from Jan. 2014 to Jan. 2016 y admitted to the hospital were selected. Totally 824 cases of Children with Mycoplasma pneumoniae and (or) C.pneumoniae infections with asthma were set as observation group, and non M.pneumoniae and (or) C.pneumoniae infections were set as control group. The clinical data of the two groups were compared, and the clinical characteristics of M.pneumoniae and C.pneumoniae infection in children with asthma were summed up. RESULTS Among 1286 cases of children with asthma, there were 824 cases of M.pneumoniae and (or) C.pneumonia infections, and the infection rate was 64.07%, of which 583 cases were M.pneumoniae infection, 201 cases of C.pneumoniae infections, and 40 cases were Mycoplasma pneumoniae and Chlamydia pneumoniae infection. The observation group with age less than 1 year old was more than that of control group, the laboratory index of eosinophil count and C- reactive protein of control group were (284.24±48.33)×10⁶/L and (6.84±0.73) mg/L, which were lower than (396.34±64.63)×10⁶/L and (7.94±0.83) mg/L of observation group, white blood cell count and procalcitonin (PCT) of observation group were (7.84±0.83)×10⁹/L and (0.72±0.07) μg/L, which were significantly higher than observation group (P<0.05), and the chest pleural effusion, cloud like changes, interstitial lung infiltration, interstitial lung and lung parenchyma infiltration, fan-shaped infiltration and lung parenchyma infiltration between the two groups had significant differences(P<0.05). The clinical manifestations of fever (96.84%), headache (60.92%), cough (71.48%), and chest pain (30.70%) of observation group were significantly higher than control group (P<0.05). Runny nose (22.13%) and wheezing rate (13.38%) in asthma children with mycoplasma pneumonia were significantly higher than 12.44% and 6.97% of Chlamydia infection in children, and diarrhea (8.92%) and vomiting (8.40%) were significantly lower than 17.41% and 14.43% of Chlamydia infection in children (P<0.05). CONCLUSION The infection rate of children with asthma and M.pneumoniae and (or) C.pneumoniae infections is higher, and has certain clinical features, which can provide a reference for the diagnosis and treatment of children with asthma and improve the accuracy of children's experimental drug selection.