Abstract: Objective: To investigate the regularity of callosal development in children and adolescent and its sex difference.Methods: The midsagittal images of 81 normal children and adolescent were selected in e-film workstation and then imported to the Photoshop.The area of the cerebrum and the corpus callosum were measured in Adobe Photoshop^® 10.0.Pearson correlation analysis and test were adopted to analyze the development of corpus callosum and the sex difference.Results: In the total samples,significant linear correlation was observed between the corpus callosum/all the subregions and the age (P<0.05-P<0.01);when the analyses were performed separately for males and females,all subregions still linearly correlated with the age except areaⅠ (P>0.05).Although significant sexual difference was found in the total callosal area,as well as in the areaⅠ,Ⅳ and Ⅵ (P<0.05-P<0.01),the difference was not statistically significant (P>0.05) after the cerebral volume was corrected.Conclusions: In normal children and adolescent,the callosal area increases with the age,and all the subregions increase simultaneously.Sex difference of callosal area may be better explained by an underlying effect of cerebral size.