Objective To improve the fixation method of indwelling needle inserted in the tail vein in rats to keep the inserted needle for a longer indwelling time. Methods One hundred healthy Wistar rats (age 5～6 months, male:female=1:1) were randomly divided into two groups: the experimental group and the control group. Rats in both groups received the same tail vein indwelling needle puncture and cannulation. The control group got the traditional fixation, namely fixed by sticking with 3M transparent dressing paste. The experimental group received in addition to the traditional fixation, a 0.1 mm-thick aluminum tube placed outside the needle fixation site. The indwelling time in the rats were recorded and analyzed. Results The indwelling time was (166.86±9.03) h and (20.24±5.04) h in the experimental and control groups, respectively (t=68.546, P<0.01). Conclusions Our improved method is safe and reliable. It can prolong the indwelling time of the punctured intravenous indwelling needle, and provides a useful rat model in studies on the complications of intravenous indwelling needle kept for a longer time.