Abstract: Abstract: Background There is a tendency for early onset of puberty in children and adolescents worldwidely. And excessive consumption of unhealthy diets such as sugary drinks may be a contributing factor.Objective To investigate the effects of early life cola and diet cola exposure on the initiation of puberty in male mice.Methods Female C57BL/6J mice were exposed to cola and diet cola on the day of detection of vaginal plugs, and the exposure continued until the onset of puberty in male offspring mice, during which time the offspring were weighed regularly, and their daily water intake and food intake were monitored. On the day of puberty initiation indexes appeared, the mice were executed, and serum, testis, and hypothalamus tissues were collected to examine the levels of hormones and expression of genes critical to the regulation of the puberty onset.Results Compared with the control group, mice in the cola group (P < 0.05) and the diet cola group (P < 0.05) had a significant increase in body weight, an increase in water intake, and a decrease in food intake, and both the increase in water intake and the decrease in food intake of mice in the diet cola group were lower than those in the cola group. Compared with the control group, the time of penile peeling was significantly earlier in the cola group (P < 0.01) and the diet cola group (P < 0.01). The testicular organ coefficient was significantly higher (P < 0.01), and spermatogenic tubule epithelial thickness was significantly increased (P < 0.01) in the cola group, while there was no significant difference in testicular organ coefficient, and spermatogenic tubule epithelial thickness was significantly increased (P < 0.05) in the diet cola group. Serum hormone levels of GnRH (P < 0.05), LH (P < 0.05), and FSH (P < 0.01) were significantly higher in the cola and diet cola groups compared to the control group. For mechanisms, mRNA expression levels of HPG axisrelated genes TTF-1, KISS-1, GPR54, and GnRH were significantly upregulated in the hypothalamic tissues of mice in the cola group and the diet cola group (P < 0.05), and the mRNA expression levels of energy metabolism-related genes POMC were significantly downregulated (P < 0.01). In testicular tissues, Cyp1b1 mRNA expression was significantly decreased (P < 0.05), whereas no significant changes were observed for Cyp19a1. Conclusion Early-life cola and diet cola exposure may promote secretion of the hormones GnRH, LH, and FSH by modulating the upstream gene TTF-1 of the HPG axis in male mice, affecting the expression of the KISS-1, GPR54, and GnRH genes in the HPG axis, which in turn modulates the expression of the Cyp1b1 gene in the testes, resulting in an earlier initiation of puberty.