Abstract: Objective To compare the effect of modified seldinger technique under the guidance of ultrasound for PICC inserttion with the traditional method of PICC catheterization(14 G needle insertion of PICC)in elderly patients with Alzheimer’s disease.Methods 60 patients with AD were divided into observation group applying PICC insertion with US and MST and con-trol group with traditional method of PICC catheterization with 30 patients in each group.The suc-cess rates of the only one puncture,catheter indwelling time and the incidence of complications dur-ing catheter indwelling were compared between the two groups.Results There were 22 patients with 7 to 12 months catheter indwelling time and 8 patients with more than 12 months in observa-tion group.There was 1 patient for 1 to 3 months catheter indwelling time,11 patients for 4 to 6 months,7 patients for 7 to 12 months and 1 patient for more than 12 months in control group.Ac-cording to the results,the difference was statistically significant(P <0.05).The successful rate of the only one puncture in observation group was 96.7% while only 53.3% in control group.So the difference was statistically significant(P <0.05).The incidence of complications during catheter indwelling was 6.7% in observation group and 50% in control group.Thus,the difference was statistically significant(P <0.05).Conclusion The PICC catheterization with modified seldinger technique under the guidance of vascular ultrasound has higher successful rate and less incidence of complications.So it is worthy of widely application.