BACKGROUND: In vivo experiments using mice play a crucial role in advancing biological and translational research due to the similarities between their biological pathways and those of humans. In this study, we utilized silicone vascular perfusion to map the venous distribution in the lower lips of mice and explored the potential for a new blood collection site in mice. METHODS: Silicone perfusion was performed in this study, revealing the venous distribution in the lower lip of mice. Additionally, we identified and refined the venous bridge as an optimal site for blood collection. RESULTS: This research identified the distribution of veins in the lower lip of mice and discovered a useful, repeatable, and minimally invasive method for blood sampling in small animals. CONCLUSIONS: This unique venous bridge represents a novel and ideal site for blood collection.