Objective　To explore the clinical diagnosis and treatment of Mycoplasma pneumoniae pneumonia complicated with pulmonary embolism in children. Method　The clinical data of Mycoplasma pneumoniae pneumonia complicated with pulmonary embolism in a child were retrospectively analyzed. Results　A 10-year-old female patient presented with cough, fever and tachypnea. The titer of Mycoplasma pneumoniae antibody was 1:320, the anti-cardiolipin antibody IgM was positive, and the D-dimer level was 42.4 μg/mL. CT pulmonary angiography suggested a pulmonary embolism. After the diagnosis of mycoplasma pneumonia and pulmonary embolism, azithromycin was given for anti-infection, warfarin and low molecular weight heparin calcium were given for anticoagulation and circulation improvement, atomization technique was given to eliminate phlegm. After 3 months of anticoagulation therapy, pulmonary embolism was cured. Conclusions　If the child with Mycoplasma pneumoniae pneumonia has dyspnea and chest pain accompanied by positive anti-cardiolipin antibody and increased D-dimer, pulmonary embolism should be considered and pulmonary artery CT angiography should be timely performed to make a clear diagnosis.