Abstract: The largemouth bass（Micropterus salmoides） is an economically important aquaculture fish. Although the growth of male and female individuals does not differ significantly, their gonadal maturation and reproduction processes can affect individual growth and are prone to problems associated with disease. Therefore, an in-depth understanding of the sex differentiation and reproduction mechanism of largemouth bass is important to achieve gender control and to improve breeding efficiency. In this study, the transcriptome of male and female gonads of largemouth bass was sequenced using RNA-seq technology. Differential gene expression analysis identified 11 737 differentially expressed genes（ DEGs） in the gonads of largemouth bass, female compared with male. Among these, 4 168 were up-regulated and 7 569 were down-regulated. The above DEGs were compared in Nr, KEGG and GO databases, and 57 GO functional annotation components and 42 KEGG secondary branching metabolic systems were obtained. In both enrichment analyses, the GO components and KEGG branching systems with high enrichment of DEGs were metabolically dominant, while the GO components and KEGG branching systems associated with sex regulation had relatively few enriched DEGs（85 and 1 803, respectively）. The results of the two enrichment methods were screened, and 62 sex-related candidate genes were identified, in which 20 were up-regulated and 42 were down-regulated. These included typical sexregulation-related gene families, such as the Dmrt family（5）, Sox family（14）, Tgf-β superfamily（4）, cytochrome P450 aromatase family（2）, 17β-estradiol dehydrogenase family（3）, and DEAD-box family（2）. In addition, the results revealed genes of sex hormone receptors（10）, the Rspo1/Wnt/β-catenin signaling pathway（4）, hormone regulators（8）, the spermatogenesis-related family（3）, TKL family（2）, and transcription factors（2）. Fifteen typical sex-related candidate genes from among the above were selected for q PCR validation, and the results showed that the expression levels of all genes, except for vasa, were consistent with the results of the transcriptome. In addition, a total of 460 783 SNPs and 78 912 INDELs were obtained from the transcriptomes of the male and female gonads of largemouth bass, and significant differences were found in the regional distribution of the loci for male and female gonad SNPs and INDELs. The results of this study provide an important reference for future functional studies of sex-related genes and the development of sex-related molecular markers.