Abstract: Sexual dimorphism refers to the morphological differentiation between males and females in the same population, such as sizes, morphological features, and colors. Cold water fish Glyptosternum maculatum, is an endemic teleost species of notable economic importance and with high potential for controlled rearing of the species in Tibet Autonomous Region. In this study, morphological measurements and related analysis were conducted on sexually mature G. maculatum to investigate their morphological differences in Tibet Autonomous Region. Results indicated the sexually mature populations indeed display really displayed significant sexual dimorphism: males exhibited significantly greater body length, weight, and males also exhibited in addition to greater tail length while females exhibited significantly greater eye diameter, body depth, trunk length, and lengths of dorsal, pectoral, pelvic, anal, and caudal fins at a given body length. Principal components analysis on 16 morphological parameters showed that the differences were largely due to features of the body shape (including lengths of body parts and fins) and the head, and differences in the above features differences contributed 76.7%. The t-statistic test on the allometry index b in the total length-weight function showed that during the breeding season, the total lengths and weights of G. maculatum females developed proportionally, while the male specimens were allometrical.