Objective To comparatively analyze CT findings of children with Mycoplasma pneumonia (MP) and children with Streptococcus pneumonia (SP). Methods CT imaging data of 70 children with simple MP (simple MP group) and 50 children with MP and SP (MP+SP group) which were confirmed by menstrual serology and blood cultures in the hospital from January 2014 to December 2016 were analyzed retrospectively. Results There was no significant difference between the two groups in diseased region (P>0.05). The incidence rates of bronchial wall thickening, reticular formation, ground glass shadow, bronchial vascular bundle thickening and fan-shaped segments of lungs were significantly higher in the simple MP group than in the MP+SP group. The incidence of pleural effusion in the simple MP group was significantly lower than that in the MP+SP group (11.43% vs. 40.00%) (P<0.05). The thickness of pleural effusion and transverse diameter of lymph node in the simple MP group were significantly smaller than those in the MP+SP group (P<0.05). Conclusion CT pulmonary interstitial change is the main finding of simple MP while intrapulmonary solid change is the main finding of MP+SP. The incidence of pleural effusion is significantly higher and lymphadenectasis is more obvious in children with MP+SP.