Abstract: [Objective] An improved preparation technology of G-banding chromosome sample was introduced. [Method] Mouse bone marrow cells were used, some key steps such as pancreatic enzyme, staining methods were improved, and the best experimental condition and methods were obtained. [Result] More and better scattered mitosis figures were obtained, and a high practical, simple and easy preparation technology of chromosome of G-banding with clear banding pattern and stable results was established. [Conclusion] The research provides a practical reference for the specification of mice chromosome specimen preparation methods, and improves the experimental teaching effect.