Abstract: OBJECTIVE To investigate the diagnostic value of serum Mycoplasma pneumoniae (MP) antibody combined with chest CT signs in pediatric Mycoplasma pneumoniae pneumonia (MPP). METHODS The clinical data of 69 children with MPP and 81 children with Streptococcus pneumonia (SP) admitted to department of Pediatric Internal Medicine, Changxing Branch of Children's Hospital Affiliated to Zhejiang University between Jun. 2019 and Jun. 2020 were retrospectively analyzed and included in the MMP and SP groups, respectively. The data such as gender, age, fever time and hospitalization time in both groups were collected. The positive rates of serum Mycoplasma pneumoniae-immunoglobulin M (MP-IgM) and MP-IgG were compared between the two groups. The chests CT manifestations of the both groups were analyzed, and the lymphadenography, pleural effusion and the incidence of chest CT signs were compared between the two groups. RESULTS The positive rates of serum MP-IgM and MP-IgG antibodies in MPP group were higher than those in SP group (P<0.05). There was no significant difference in the incidence of lymphadenography between the two groups. The incidence of pleural effusion, the average transverse diameter in lymphadenography and thickness of pleural effusion in MPP group were lower than those in SP group (P<0.05). The incidence of chest CT signs including thickening of bronchial walls and bronchial vascular bundles, reticular shadow, ground-glass opacity in MPP group was higher than that in SP group (P<0.05). CONCLUSION The serum MP antibodies combined with chest CT signs could better distinguish MPP from SP in children, which had relatively higher clinical value.