Abstract: Objective To find suitable adjustment period of dialysis machine ultrafiltration function. Methods 28 dialysis machines in hemodialysis center of Beijing TongRen hospital ,Capital medical university, were selected. Ultrafiltration errors in different times were measured. The samples were divided into 5 groups by different testing times. Ultrafiltration errors were compared among time groups. Then the samples were divided in 2 groups by different hemodialysis machine brands. Ultrafiltration errors were compared among different brands groups. Results 1.Compared among different testing time groups, ultrafiltration errors were significant different between immediate after adjustment group and 6 months later group，9 months later group, 12 months later group(P＜0.05).The differences of ultrafiltration errors between 3 months later group and 6 months later group ,9 months later group, 12 months later group were significant(P＜0.05). 2.Compared in different machine brand groups, ultrafiltration errors between Fresenius and Braun machine in 9 months later group and 12 months later group have significant difference(P＜0.05). Conclusion It is reasonalbe to adjust hemodialysis machine ultrafiltration function every 6 months.

Key words: Hemodialysis machine, ultrafiltration, adjustment