Objective To analyze the clinical characteristics and laboratory indexes of pneumonia complicated with pertussis syndrome in Suzhou area in order to provide the basis for rational treatment.Methods Children who had been hospitalized at Department of Respiratory,Children's Hospital of Soochow University during January 2012 to October 2016 were enrotled and diagnosed as pneumonia complicated with pertussis syndrome.A total of 236 cases were enrolled.Multiple pathogen detection and clinical information were collected in all patients.The subjects were divided into 28 days-＜ 3 months group,3-＜ 6 months old group,6-＜ 12 months old group and ≥ 12 months old group.The clinical data of children in each age group were retrospectively analyzed.Results Pneumonia complicated with pertussis syndrome was easy to occur within 6 months of infants,with the highest incidence in the 3-＜ 6 months group,there was a significant difference among the different age groups (x2 =231.870,P ＜ 0.05) [28 d-＜ 3 months group:5.3％ (102/1 910 cases),3-＜6 months group:5.7％ (76/1 341 cases),6-＜ 12 months group:2.0％ (36/1 762 cases),≥12 months group:0.4％ (22/5 304 cases)].The patients could become sick all the year round,with the highest incidence in summer[2.6％ (72/2 740 cases)in spring,3.7％ (96/2 611 cases)in summer,2.1％ (56/2 749 cases) in autumn,and 0.48％ (12/2 487 cases)in winter],and there were significant differences among the different seasons (x2 =62.380,P ＜0.001).Clinical symptoms were paroxysmal spasmodic cough,33.0％ (78/236 cases) of the performance with wheezing,mainly in the older than 3 months group.The incidence of fever was positively correlated with age(x2 =12.938,P ＜ 0.05).Peripheral white blood cell count and lymphocyte percentage increased,and the 3-＜ 6 months old group increased markedly.White blood cell count as high as (19.01 ± 11.99) × 109/L,the highest percentage of lymphocytes was up to 0.80,platelets were significantly increased in more than 80％ of children.The incidence of C-reactive protein (CRP) was negatively correlated with age,28 days-＜ 3 months group more prone to have high CRP.Pulmonary inflammatory pathology showed multiple pulmonary involvement by chest radiography,and it was more likely to occur in 28 d-＜ 3 months group.Viruses,bacteria and mycoplasma pneumoniae (MP) could cause pneumonia associated with pertussis syndrome,and mixed infection occurred in 56 cases.The top three pathogens were rhinovirus,MP and Streptococcus pneumoniae,and mixed infection was more prone to occur in 28 d-＜ 3 months group.Conclusion Pneumonia complicated with pertussis syndrome is easy to occur within 6 months of infants,with the highest incidence in summer.Viruses,bacteria and MP all could cause pneumonia associated with pertussis syndrome,and mixed infection could occur in some cases.The top three pathogens are rhinovirus,MP and Streptococcus pneumoniae.