Abstract: Objective To study the incidence of simple obesity of children in kindergarten and the level of 31 kinds of whole blood carnitine of children with simple obesity, to explore the relationship between the level of whole blood carnitine and childhood obesity, and to provide the scientific evidence for clinical diagnosis and treatment of children with simple obesity. Method A total of 3516 children aged 3-6 years old were performed physical examination. Among the 3516 children, 54 children with simple obesity were selected as observation group and 54 children with normal weight were selected as control group. The levels of carnitine of the two groups were detected by Tandem mass spectrometry (MS/MS). The data was processed by SPSS11.0 statistical software package.Result There was imbalance of the level of whole blood carnitine in the twogroups. The level of CO、C2、C3、C5-OH、C5、C5:1、C8:1、C10:2、C14 OH、C16、C16:1、C18:1、C18:2 of observation group were higher than those of the control group. The difference was statistically significant (P< 0.05). There was no difference in the levels of C3 DC、C4、C5 DC、C6、C6 DC、C8、C10、C10:2、C12、C12:1、C14、C14:1、C14:2、C16 OH、C16:1 OH、C18、C18 OH、C18:1 OH between the two groups (P> 0.05).Conclusion The whole blood carnitine levels of children with simple obesity is higher than the children with normal weight. Dynamic monitoring of blood carnitine levels can provide a scientific evidence for clinicians to make intervention to children with simple obesity.