Objective To provide a practical device and skills for injection of caudal veins, knee joints and belly cavity of rats. Method Using plastic bottle for injection and haemostatie forceps to make a simple device for holding rats. With this device, the rats were treated by injection of caudal veins, knee joints or belly cavity. Result The rats could be hold well in the device. With the device, the injection of caudal veins, knee joints and belly cavity could be finished smoothly, quickly and safely. Conclusion This device is economical, practical and easy to be made. It is a good device for holding rats.