Objective To analyse the causes of native arterio-venous fistula aneurysm and to find prevention measures. Methods In 80 hemodialysis patients, there are 9 snuff-box arteriovenous fistulas and 71 brachiocephalic fistulas. Among them 16 patients had to made second fistulas in the same arm. Spring tape around the arm or applying pressure and adhesive tape on the puncture site were used to stop bleeding after dialysis. Results There are 13 aneurysms and 1 pseudoaneurysm in 80 hemodialysis patients. In these patients,12 of them used spring tape and 2 used adhesive tape on the site after hemodialysis. six patients have local needling. Tow aneurysms were found in each surgical way of fistula. Conclusion Arterial-venous fistula aneurysm formation is related with repeated localised puncture site, postdialysis haemostasis, atherosclerotic and so on. 