Objective To provide references for diagnosis of abnormal renal morphology, and to establish the range of the normal renal cortex thickness using CT measurement in different age groups, so as to obtain a practicable method for clinical measurement. Methods A total of 204 children without kidney disease and drug-induced kidney injury were examined with CT, and were divided into 0—, 1—, 3—, 7— and 13—16 year-old groups. The renal cortical and parenchymal thickness and renal size were measured on CT images and were analyzed statistically. Results The renal cortex thickness in 5 groups was (0.41±0.09)cm, (0.48±0.09)cm, (0.54±0.12)cm, (0.65±0.13)cm and (0.76±0.18)cm, respectively, and statistical difference was found between each two groups (all P0.05). The age and renal cortex thickness correlated significantly (right kidney: r=0.65, left kidney: r=0.65, both P0.05). The ratio of the renal cortex thickness to renal parenchyma thickness had the lowest correlation with age (right kidney: r=0.19, left kidney: r=0.16, both P0.05). Conclusion Renal cortex thickness of normal kidney increases with age, but the change of the ratio of thickness in renal cortex to renal parenchyma with age is not significant. The research results provide an important CT anatomic basis for diagnosis of child renal diseases.