In order to accelerate the renewal of largemouth bass (Micropterus salmoides), a complete diallel crossing experiment was carried out using the introduced American population (US) and the domestic cultured population (YZ) as the base populations, and four paired combinations of USUS, USYZ, YZUS, and YZYZ were obtained, and the one-year-old fish growth performances of their offspring were compared. The results indicated that USYZ had a significant heterosis (P<0.05) in body weight, standard length, and absolute weight gain rate, and consistently had the highest coefficient of variation. Meanwhile, two hybrid groups (USYZ, and YZUS) had median parental heterosis for all growth traits. The body weight, standard length, total length, head length and body height of the USYZ hybrids have supernatural hybrid heterosis and were higher than those traits of YZUS hybrids. Additionally, the results of the path analysis revealed a highly significant positive correlation between total length, body width, body height, and body weight of the offspring (P<0.01); different from USUS, the coefficient of determination for body weight via body width was higher than that via body height in USYZ, YZUS, and YZYZ. Based on diallel cross mating design, the best mating group was investigated in terms of growth traits of hybrid offspring, so as to provide a basis for genetic improvement and breeding of M. salmoides in practice.