Abstract: Objective To analyze the characteristics of serum vancomycin concentrations and its clinical therapeutic effects. Methods Serum vancomycin concentrations of 59 children diagnosed with severe Gram positive cocci pneumonia and treated with vancomycin were retrospectively analyzed. Vancomycin concentrations, biochemical values and disease status of patients were analyzed. Results The serum vancomycin concentrations of severe Gram positive cocci pneumonia children accompanied by acyanotic congenital heart disease was significantly higher than those without congenital heart disease, ( 12 . 12 mg/L vs 7 . 76 mg/L, P= 0 . 008 ). The therapeutic effect of 40 - 60 mg/(kg·d) dosage group was significantly higher than that of < 40 mg/(kg·d) group ( 89 . 47 % vs 46 . 15 %, P= 0 . 004 ), while the therapeutic effect was similar between 40 - 60 mg/(kg·d) and > 60 mg/(kg·d) dosage group. Acute liver function damage and moderate/severe anemia may be risk factors for poor therapeutic effects to severe Gram positive cocci pneumonia children (P < 0 . 05 ). Conclusions Severe Gram positive cocci pneumonia children accompanied by acyanotic congenital heart disease may lead to a high serum vancomycin concentration. The 40 - 60 mg/(kg·d) dosage group may reach a satisfactory therapeutic effect. For children with acute liver function damage and moderate/severe anemia, a close monitoring to the state of illness is recommended to prevent poor prognosis.