Objective:To study the relationship between the indwelling time of intravenous catheter system injection of different types of drugs and degree of vascular injury. Methods:Totally 60 New Zealand rabbits were selected as study samples and evenly divided into three groups randomly. The veins at the edges of the two ears were taken out as the tested blood vessels for the infusion with intravenous catheter system. The three groups were injected respectively with doxorubicin,20% mannitol and physiological saline once daily,and then blocked with heparin salt water. After intraperitoneal anesthesia,pathological sections were prepared by taking live samples from the ear vein where intravenous catheter system puncturing on the 2 nd,4 th,6 th,8 th and 7 th day of transfusion,and changes of vascular and peri-vascular tissues were observed under microscope. Results:In the same indwelling time,the inflammatory response of the three groups was compared:there were no differences at the 2nd,8th and 10th day(P > 0.05),but significant differences were observed on the 4 th,6 th day(P < 0.05). Comparison of thrombosis showed that there were no differences at the 2 nd,and,4 th day(P > 0.05)but with markable difference observed at the 6 th,8 th and,10 th day(P < 0.05). The comparison of inflammatory response and thrombosis situation in different parts in the same group showed obviously difference(P < 0.05). Conclusion:The indwelling time of Intravenous Catheter System should be set according to the type of drugs. Two-day of indwelling time is suitable for strong irritant substances,which should not be more than 72 h. The indwelling time of the weak irritant drugs by intravenous catheter system injection may be appropriate to extend with limitation of 7 days.