Abstract: Objective To explore the relationship between the levels of amino acids in whole blood and children obesity by the incidence of simple obesity among children in provincial kindergarten in Shijiazhuang and provide the scientific evidence for clinical diagnosis and treatment of children with simple obesity. Method A total 54 children with simple obesity (observation group) were randomly selected from 3516 3-6 years old children who participated the physical examination in provincial kindergarten. According to the 1:1 matching principle, 54 children with normal weight were also selected as the control group. All of the children were tested the levels of amino acids in whole blood by tandem mass spectrometry (MS/MS). SPSS 11.0 statistical software package was used to analyze the data. Result There was difference in the level of the whole blood amino acid between the two groups. The levels of ALa, Val, Orn, Leu, Met, Phe and Tyr were higher of observation group than those of the control group. The difference was statistically significant (P<0.05). There was no statistical difference (P> 0.05) in the levels of Gly, Arg, Cit and Pro between the two groups.Conclusion The whole blood amino acid levels of children with simple obesity was higher than the normal weight children. To dynamic monitor the whole blood amino acid levels can provide a scientific evidence for doctors to prevent the simple obesity among children.