In this study, we analyzed morphological characteristics for 178 individuals of Scatophagus argus collected from 2011 to 2013. Based on the analysis of the morphological index system and R-cluster analysis, the results indicated that S.argus could be classified by "body size"and "head feature". On the basis of this analysis, 11 characteristics were normalized and further used for stepwise discrimintion. Five characteristics were selected: snout length/head length, eye distance/head length, body breadth/body length, body depth/body length and head depth/body length.Thus the sex discriminant equation was built for classifying 178 samples and the accuracy rate was 85.96%. T-test showed that three standardized characteristics between male and female populations were significantly different (P<0.05), except for eye distance/head length and body breadth/body length. Therefore, we concluded that female S.argus were superior to males in the respects of body depth, head and snout length.