Sex determination is considered the first and most important process in the identification of unknown skeletal remains. The skull is one of bones with high accuracy to discriminate sexes, but there is no dimorphic studies of Korean skull by discriminant function analysis. The aim of this study was to build and provide an easy and accurate discriminant equation to sex determination by using three-dimensional skull images of Korean. Computed tomography images from 102 cadavers were reconstructed three-dimensional images by computer program. We measured 44 variables using the template in computer program and variables were sorted out items with high accuracy and reliability by intraclass correlation coefficient (ICC), Cohen's d value, and receiver operating characteristic (ROC) curve. The equation with the highest accuracy had 82.7% in males, 82.2% in females, it was constituted bizygomatic diameter, cranial base length, biauricular breadth, upper facial breadth, frontal chord, foramen magnum breadth, and right mastoid length. The cross-validated accuracy had 76.5%~86.7% using 3D skull images in Koreans. The value of variables that matches the other population group study, most of variables had a statistically significant difference among population groups. Male skulls in Koreans were smaller than those in European and female skulls were bigger than in Asian. This result should be helpful to determine sex in Koreans.