The giant freshwater prawn (GFP) is one of the largest freshwater shrimps in the world, widely distributed in the tropical and subtropical regions of Southeast Asia, the Indian Ocean, and the Pacific Ocean. It has become an important cultured species in China since its introduction because of its wide diet, high growth rate, and high economic value. However, the GFP shows slower growth and poor resistance primarily resulting from an inbreeding depression and farming at high density. One male morphotype named as "old males" or "old blue claw" is present commonly among blue claw males, exhibiting developed second legs and carapace with a dark blue body color, and its economic value is very low. Therefore, improved varieties are urgently needed through selective breeding. The body weight is one of the most important traits for selective breeding, which are closely correlated with morphometric traits. To investigate the correlation and differences in phenotypic traits among cultured groups of , a correlation analysis among 12 phenotypic traits, stepwise multiple regression, and path coefficient analysis on body weight and morphometric traits were performed on 490 individuals of selected from Jiangsu Shufeng Prawn Breeding Co. Ltd. representing three cultured groups:females, males, and old males. Compared with the phenotypic traits in the industry standard published in 2002, the growth performance of the present GFP variety has been greatly improved after years of breeding, and a new industry standard for the new variety should be developed and published. The results of correlation analysis and path analysis showed that 1) except for numbers of dorsal and ventral rostrum teeth, the coefficients between the other nine traits and body weight showed extremely significant positive correlations (<0.01); 2) the key morphometric traits attributed to body weight were different in different groups, but body length, carapace length, and length of second leg were the key traits in the three groups. We estimated the multiple regression equations for each group according to the key traits. For each group, the direct effect of each key morphometric trait on body weight was less than the total indirect effects through the other key traits. The hierarchical cluster analysis and principal component analysis showed that females and males clustered together, and their morphometric traits were similar; the highest variation existed between females and old males. Abdominal characters (including abdominal length, abdominal width, and abdominal depth), total length, body length, and length of second leg contributed the most to the differences among the three groups. Among the three groups, females show advantages in the growth of the abdomen, whereas old males have more developed second legs. The present study can provide data for reference not only for the selective breeding of but also for its basic biology and the development of industry standard.