Abstract:Two different geographical populations of largemouth bass Micropterus salmoides from Guangdong and Taiwan were randomly selected. The differences in morphological traits and their effects on body weights between the two populations were analyzed by multivariate analysis. Results showed that the significant differences were observed in the middle and back sections of fish body. The contribution rates of the first three principal components were 95.8%. In the scatter plot of the scores of the first two principal components, the two populations could be completely distinguished due to the low overlap area. The morphological traits of Guangdong population and Taiwan population had similar effects on the body weights. The significantly direct effects were found in body height, length from origin of pectoral to dorsal fin, length from origin of anal to dorsal fin, length from origin of anal fin to terminus of dorsal fin, and length from terminus of dorsal fin to origin of tail fin, which were the crucial factors affecting the body weights of the two geographical populations of Micropterus salmoides. A theoretical basis for body weight selection of Micropterus salmoides was provided.