Abstract: Objectives　To analyze the relationship between the different dosage of vancomycin and its blood concentration in children in pediatric intensive care unit (PICU), the relationship between different valley concentrations and therapeutic efficacy and the adverse reactions. Methods　The clinical data of 72 children admitted to PICU and treated with vancomycin from January 2013 to June 2016 were retrospectively reviewed. The vancomycin doses in 58 cases was 40 mg/ (kg·d) and were 60 mg/(kg·d) 14 patients. In the subjects treated at 40 mg/(kg·d), administration by q12h were in 19 cases, q8h in 22 cases and q6h in 17 cases. After vancomycin was administered at least 4 doses, blood samples were collected, and the valley concentration was determined within 30 min before administration of vancomycin and peak concentration was determined within 30-60 min after administration of vancomycin. The concentration of vancomycin in plasma was detected by high performance liquid chromatography (HPLC). Results　When vancomycin was administrated at 40 mg/(kg·d), there were no difference in valley concentration and peak concentration among the three groups of q12h, q8h, and q6h (P>0.05).  The effective rate was not different between valley concentration ≤5 μg/mL and >5 μg/mL of vancomycin (81.8% vs. 84.0%, P>0.05). Compared with vancomycin 40 mg/(kg·d) group (q8h), the valley concentration and peak concentration in 60 mg/(kg·d) group were significantly increased (P<0.05). Conclusion　It was difficult to reach a valley concentration of 10 μg/mL by using conventional doses of vancomycin. Thus, in order to achieve effective concentration and reduce adverse reactions, the dosage of vancomycin can be increased, and the times of administration can also be increased.