【Objective】 To investigate the reference values of serum cystatin C within the healthy preschool children. 【Method】 The automatic biochemical analyzer(OLYMPUS AU2700)was used to detect the level of serum cystatin C of 474 healthy preschool children and 172 normal adults.Then the data were analyzed with statistical methods. 【Results】 The value of cystatin C of infant group, child care group,preschool group and normal adult group were 0.62~1.74,0.47~1.15,0.41~0.97 mg/L and 0.46~1.02 mg/L,respectively.Infant group,child care group and normal adult group reference values were significantly different (P<0.05).There was no difference between preschool group and normal adult group.Each of the groups were compared by sex,between boys and girls within each group of Cys C reference values were not significantly different (P>0.05).Normal adult reference range for the control group,infant group,child care group overrun detection rates were 56.8%,11.1%. 【Conclusions】 Infant group, child care group and adult group can adopt different reference values of serum cystatin C,preschool group and normal adult group can use the same.There is no difference between boys and girls for serum cystatin C.