Objective To analyze the characteristics of cardiovascular lesion caused by Mycoplasma pneumoniae (MP) infection in children with Kawasaki disease (KD), and provide guidance for clinical diagnosis and treatment. Methods Clinical data of children with KD who were admitted to the department of pediatric cardiology of a tertiary general hospital from January 2018 to March 2021 were analyzed retrospectively, patients were divided into KD complicated with MP infection group(KD-MP group)and KD without MP infection group (KD group), differences in platelet parameters, coagulation-related indexes, myocardial enzyme spectrum and incidence of adverse outcomes between two groups of children were compared. Results A total of 270 children with KD were included in analysis, including 70 cases in KD-MP group and 200 cases in KD group. The median level of mean platelet volume (MPV) in KD-MP group was higher than that in KD group (10.00 [9.08, 11.00] fL vs 9.60 [8.83, 10.68] fL, P < 0.05). The proportions of coronary artery lesion, mild coronary artery dilatation and pericardial effusion in KD-MP group were 55.71%, 47.14% and 15.71% respectively, which were higher than 38.50%, 30.50% and 5.50% in KD group (all P < 0.05). Conclusion KD patients complicated with MP infection are more likely to suffer from coronary artery lesion and pericardial effusion, and face a greater risk of cardiovascular lesion, clinicians should take anti-infective treatment in time.