Abstract: 　Objective　To study the clinical characteristics and laboratory findings of Mycoplasma pneumoniae (MP) and EBV infection in children and provide reference for clinical diagnosis and treatment. Methods　One hundred and twenty two (122) hospitalized children with pathogen detection of MP and EBV double positive in hospitalized children with pneumonia from May 2013 to April 2014 (n=2213) were recruited as mixed infection group. In the mixed infection group, patients were further devided into high EBV mixed infection group if the EBV DNA copies were more than 1.0×104 copies/ml and the low EBV mixed infection group when EBV DNA copies were less than 1.0×104 copies/ml. And another 45 hospitalized children with MP pneumonia were rectuited as control group. Clinical data and laboratory findings of all children were collected and analyzed. Results　The mixed infection rate of MP and EBV was 5.51% (122/2213). As children getting older, the incidence of mixed infection was increased (χ2=84.08, P<0.001). And the mixed infection incidence in the lobar pneumonia group was significantly higher than the bronchopneumonia group (χ2=37.44, P<0.001). The incidence of ALT and CK-MB elevated, lobar pneumonia, average fever days and hospitalization days in mixed infection with the high EBV copies group were significantly higher than those in the low EBV copies group and the control group (both P<0.05). The incidence of ALT and CK-MB elevated, average fever days and hospitalization days in mixed infection with the high EBV copies group were significantly higher than those of the low EBV copies group and the control group (all P<0.05). Conclusion　The mixed infection of MP and EBV could aggravate the injury both in and out of the lung. Number of EBV copies plays an important role in the degree of injury both inside and outside the lung due to pneumonia with mixed infection of MP and EBV. When a patient with MP pneumonia complains with severe clinical symptoms and obvious injury outside the lung, EBV detection, especially quantitative detection of EBV DNA copies could be beneficial for clinical diagnosis and treatment.