Abstract: Objective:To investigate the structural asymmetry of the insula and its deep structure between the left and right hemispheres.Methods:Using e-film workstation based on computer,cross-section MRI scan images of the brain among thirty cases of healthy population were chosen,images which involve the insula were impoted into photoshop 10.0 software to measure,originating the data of the distance between the area of insula and the midsagittal plane,then we come to the conclusion of 95% confidence interval of typical sections' distance variations between both sides under analysis of SPSS 13.0 statistical software.Results:On each typical sections,the mean of distances from the midsagittal plaue to central insular sulcus,central insular sulcus,anterior periinsular sulcus and inferior periinsular sulcus is dominant in 88 percent of sections in the left side.Significant left asymmetry were indentified in the central insular sulcus in which Z value from-3 to 15 mm sections,anterior periinsular sulcus in which Z value from 0 to-9 mm sections and inferior periinsular sulcus in which Z value from-9 to 9 mm sections (P<0.05-P<0.01).The variation was not significant in the remain sections of sulcus (P>0.05).Conclusions:The left insula and the area of deep structure was structural asymmetry in general pattern.Whether there is founctional asymmetry in the regional structures,and whether structural asymmetry is correlated to other regional structural and founctional asymmetry,depending further study.