The invention discloses a method for good breed group selection breed conservation of oreochromis mossambicus. Two groups of different character ratios of the body length to the body height and the body length to the body width of oreochromis mossambicus are obtained, two groups of selected character ratio standard sections are obtained through joint analysis of the body weight and the variation coefficient of oreochromis mossambicus, and the character ratios are utilized to select the standard sections to serve for the good breed selection breed conservation method. The method overcomes the shortcoming that only large individuals are selected while genotype impurity variation which is genetic variation is neglected during the good breed conservation so that the germ plasm is impure; it is guaranteed that offspring bred by selected good breed parents have the advantages of quick growth, uniform specifications and high genetic stability, and the degradation caused by the excellent characteristics after the breeding replacement of a plurality of generations can be effectively avoided.