【Abstract】 Objective To provide a device and an effective method for tail intravenous injection on mice. Methods Doing the tail intravenous injection on mice with the self-designed device which consist of constant temperature part, lighting part and holding part, than compare the difficulty and time of injection with and without the device. Results It's faster and more exact on tail intravenous injection on mice with the self-designed device. Conclusion This self-designed device can significantly improve the efficiency and decrease the injection time.