Production and consumption of Nile tilapia (Oreochromis niloticus) have been growing. Insulin like growth factors-1(IGF-1) is a hormone that affects the weight of animals. To produce high-quality Nile tilapia, traditional breeding combined with molecular marker technology to assist selective breeding has long become an effective means of cultivating new fish strains. Moreover, molecular markers or genes related to important economic traits can be found with the help of molecular-assisted selection breeding. A total of 152 fish fin samples were collected from Janghang Fishing Ground and classified according to their weight and sex (good male-35, bad male-35, medium male-12, good female-35, and bad female-35). A total of 9 SNPs (single nucleotide polymorphism) of Nile tilapia IGF-1 were identified in this study, One SNP is in the promoter, three SNPs are in the 5’UTR, and five SNPs are in the 3’UTR. By analyzing the correlation between body weight and GBs, effective GBs were selected. This study aims to improve the Nile tilapia species with the help of molecular markers in the future and to select fast-growing new strains, shorten the breeding cycle, achieve maximum economic benefits, and realize the important economic traits of tilapia. The best combination and strengthened tilapia breeding technology system provides a reference for molecular genetics. It also provides a guarantee and basis for future human protection of species diversity, food and nutrition safety, and selection of high-quality species breeding.